[MODERATION] User blocking

- Add the ability to block a user via their profile page. - This will unstar their repositories and visa versa. - Blocked users cannot create issues or pull requests on your the doer's repositories (mind that this is not the case for organizations). - Blocked users cannot comment on the doer's opened issues or pull requests. - Blocked users cannot add reactions to doer's comments. - Blocked users cannot cause a notification trough mentioning the doer. Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/540 (cherry picked from commit 687d852480388897db4d7b0cb397cf7135ab97b1) (cherry picked from commit 0c32a4fde531018f74e01d9db6520895fcfa10cc) (cherry picked from commit 1791130e3cb8470b9b39742e0004d5e4c7d1e64d) (cherry picked from commit 37858b7e8fb6ba6c6ea0ac2562285b3b144efa19) (cherry picked from commit a3e2bfd7e9eab82cc2c17061f6bb4e386a108c46) (cherry picked from commit 7009b9fe87696b6182fab65ae82bf5a25cd39971) Conflicts: https://codeberg.org/forgejo/forgejo/pulls/1014 routers/web/user/profile.go templates/user/profile.tmpl (cherry picked from commit b2aec3479177e725cfc7cbbb9d94753226928d1c) (cherry picked from commit e2f1b73752f6bd3f830297d8f4ac438837471226) [MODERATION] organization blocking a user (#802) - Resolves #476 - Follow up for: #540 - Ensure that the doer and blocked person cannot follow each other. - Ensure that the block person cannot watch doer's repositories. - Add unblock button to the blocked user list. - Add blocked since information to the blocked user list. - Add extra testing to moderation code. - Blocked user will unwatch doer's owned repository upon blocking. - Add flash messages to let the user know the block/unblock action was successful. - Add "You haven't blocked any users" message. - Add organization blocking a user. Co-authored-by: Gusted <postmaster@gusted.xyz> Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/802 (cherry picked from commit 0505a1042197bd9136b58bc70ec7400a23471585) (cherry picked from commit 37b4e6ef9b85e97d651cf350c9f3ea272ee8d76a) (cherry picked from commit c17c121f2cf1f00e2a8d6fd6847705df47d0771e) [MODERATION] organization blocking a user (#802) (squash) Changes to adapt to: 6bbccdd177 Improve AJAX link and modal confirm dialog (#25210) Refs: https://codeberg.org/forgejo/forgejo/pulls/882/files#issuecomment-945962 Refs: https://codeberg.org/forgejo/forgejo/pulls/882#issue-330561 (cherry picked from commit 523635f83cb2a1a4386769b79326088c5c4bbec7) (cherry picked from commit 4743eaa6a0be0ef47de5b17c211dfe8bad1b7af9) (cherry picked from commit eff5b43d2e843d5d537756d4fa58a8a010b6b527) Conflicts: https://codeberg.org/forgejo/forgejo/pulls/1014 routers/web/user/profile.go (cherry picked from commit 9d359be5ed11237088ccf6328571939af814984e) (cherry picked from commit b1f3069a22a03734cffbfcd503ce004ba47561b7) [MODERATION] add user blocking API - Follow up for: #540, #802 - Add API routes for user blocking from user and organization perspective. - The new routes have integration testing. - The new model functions have unit tests. - Actually quite boring to write and to read this pull request. (cherry picked from commit f3afaf15c7e34038363c9ce8e1ef957ec1e22b06) (cherry picked from commit 6d754db3e5faff93a58fab2867737f81f40f6599) (cherry picked from commit 2a89ddc0acffa9aea0f02b721934ef9e2b496a88) (cherry picked from commit 4a147bff7e963ab9dffcfaefa5c2c01c59b4c732) Conflicts: routers/api/v1/api.go templates/swagger/v1_json.tmpl (cherry picked from commit bb8c33918569f65f25b014f0d7fe6ac20f9036fc) (cherry picked from commit 5a11569a011b7d0a14391e2b5c07d0af825d7b0e) (cherry picked from commit 2373c801ee6b84c368b498b16e6ad18650b38f42) [MODERATION] restore redirect on unblock ctx.RedirectToFirst(ctx.FormString("redirect_to"), ctx.ContextUser.HomeLink()) was replaced by ctx.JSONOK() in 128d77a3a Following up fixes for "Fix inconsistent user profile layout across tabs" (#25739) thus changing the behavior (nicely spotted by the tests). This restores it. (cherry picked from commit 597c243707c3c86e7256faf1e6ba727224554de3) (cherry picked from commit cfa539e590127b4b953b010fba3dea21c82a1714) [MODERATION] Add test case (squash) - Add an test case, to test an property of the function. (cherry picked from commit 70dadb1916bfef8ba8cbc4e9b042cc8740f45e28) [MODERATION] Block adding collaborators - Ensure that the doer and blocked user cannot add each other as collaborators to repositories. - The Web UI gets an detailed message of the specific situation, the API gets an generic Forbidden code. - Unit tests has been added. - Integration testing for Web and API has been added. - This commit doesn't introduce removing each other as collaborators on the block action, due to the complexity of database calls that needs to be figured out. That deserves its own commit and test code. (cherry picked from commit 747be949a1b3cd06f6586512f1af4630e55d7ad4) [MODERATION] move locale_en-US.ini strings to avoid conflicts Conflicts: web_src/css/org.css web_src/css/user.css https://codeberg.org/forgejo/forgejo/pulls/1180 (cherry picked from commit e53f955c888ebaafc863a6e463da87f70f5605da) Conflicts: services/issue/comments.go https://codeberg.org/forgejo/forgejo/pulls/1212 (cherry picked from commit b4a454b576eee0c7738b2f7df1acaf5bf7810d12) Conflicts: models/forgejo_migrations/migrate.go options/locale/locale_en-US.ini services/pull/pull.go https://codeberg.org/forgejo/forgejo/pulls/1264 [MODERATION] Remove blocked user collaborations with doer - When the doer blocks an user, who is also an collaborator on an repository that the doer owns, remove that collaboration. - Added unit tests. - Refactor the unit test to be more organized. (cherry picked from commit ec8701617830152680d69d50d64cb43cc2054a89) (cherry picked from commit 313e6174d832501c57724ae7a6285194b7b81aab) [MODERATION] QoL improvements (squash) - Ensure that organisations cannot be blocked. It currently has no effect, as all blocked operations cannot be executed from an organisation standpoint. - Refactored the API route to make use of the `UserAssignmentAPI` middleware. - Make more use of `t.Run` so that the test code is more clear about which block of code belongs to which test case. - Added more integration testing (to ensure the organisations cannot be blocked and some authorization/permission checks). (cherry picked from commit e9d638d0756ee20b6bf1eb999c988533a5066a68) [MODERATION] s/{{avatar/{{ctx.AvatarUtils.Avatar/ (cherry picked from commit ce8b30be1327ab98df2ba061dd7e2a278b278c5b) (cherry picked from commit f911dc402508b04cd5d5fb2f3332c2d640e4556e) Conflicts: options/locale/locale_en-US.ini https://codeberg.org/forgejo/forgejo/pulls/1354 (cherry picked from commit c1b37b7fdaf06ee60da341dff76d703990c08082) (cherry picked from commit 856a2e09036adf56d987c6eee364c431bc37fb2e) [MODERATION] Show graceful error on comment creation - When someone is blocked by the repository owner or issue poster and try to comment on that issue, they get shown a graceful error. - Adds integration test. (cherry picked from commit 490646302e1e3dc3c59c9d75938b4647b6873ce7) (cherry picked from commit d3d88667cbb928a6ff80658eba8ef0c6c508c9e0) (cherry picked from commit 6818de13a921753e082b7c3d64c23917cc884e4b) [MODERATION] Show graceful error on comment creation (squash) typo (cherry picked from commit 1588d4834a37a744f092f2aeea6c9ef4795d7356) (cherry picked from commit d510ea52d091503e841d66f2f604348add8b4535) (cherry picked from commit 8249e93a14f628bb0e89fe3be678e4966539944e) [MODERATION] Refactor integration testing (squash) - Motivation for this PR is that I'd noticed that a lot of repeated calls are happening between the test functions and that certain tests weren't using helper functions like `GetCSRF`, therefor this refactor of the integration tests to keep it: clean, small and hopefully more maintainable and understandable. - There are now three integration tests: `TestBlockUser`, `TestBlockUserFromOrganization` and `TestBlockActions` (and has been moved in that order in the source code). - `TestBlockUser` is for doing blocking related actions as an user and `TestBlockUserFromOrganization` as an organisation, even though they execute the same kind of tests they do not share any database calls or logic and therefor it currently doesn't make sense to merge them together (hopefully such oppurtinutiy might be presented in the future). - `TestBlockActions` now contain all tests for actions that should be blocked after blocking has happened, most tests now share the same doer and blocked users and a extra fixture has been added to make this possible for the comment test. - Less code, more comments and more re-use between tests. (cherry picked from commit ffb393213d2f1269aad3c019d039cf60d0fe4b10) (cherry picked from commit 85505e0f815fede589c272d301c95204f9596985) (cherry picked from commit 0f3cf17761f6caedb17550f69de96990c2090af1) [MODERATION] Fix network error (squash) - Fix network error toast messages on user actions such as follow and unfollow. This happened because the javascript code now expects an JSON to be returned, but this wasn't the case due to cfa539e590127b4953b010fba3dea21c82a1714. - The integration testing has been adjusted to instead test for the returned flash cookie. (cherry picked from commit 112bc25e548d317a4ee00f9efa9068794a733e3b) (cherry picked from commit 1194fe4899eb39dcb9a2410032ad0cc67a62b92b) (cherry picked from commit 9abb95a8441e227874fe156095349a3173cc5a81) [MODERATION] Modernize frontend (squash) - Unify blocked users list. - Use the new flex list classes for blocked users list to avoid using the CSS helper classes and thereby be consistent in the design. - Fix the modal by using the new modal class. - Remove the icon in the modal as looks too big in the new design. - Fix avatar not displaying as it was passing the context where the user should've been passed. - Don't use italics for 'Blocked since' text. - Use namelink template to display the user's name and homelink. (cherry picked from commit ec935a16a319b14e819ead828d1d9875280d9259) (cherry picked from commit 67f37c83461aa393c53a799918e9708cb9b89b30) Conflicts: models/user/follow.go models/user/user_test.go routers/api/v1/user/follower.go routers/web/shared/user/header.go routers/web/user/profile.go templates/swagger/v1_json.tmpl https://codeberg.org/forgejo/forgejo/pulls/1468 (cherry picked from commit 6a9626839c6342cd2767ea12757ee2f78eaf443b) Conflicts: tests/integration/api_nodeinfo_test.go https://codeberg.org/forgejo/forgejo/pulls/1508#issuecomment-1242385 (cherry picked from commit 7378b251b481ed1e60e816caf8f649e8397ee5fc) Conflicts: models/fixtures/watch.yml models/issues/reaction.go models/issues/reaction_test.go routers/api/v1/repo/issue_reaction.go routers/web/repo/issue.go services/issue/issue.go https://codeberg.org/forgejo/forgejo/pulls/1547 (cherry picked from commit c2028930c101223820de0bbafc318e9394c347b8) (cherry picked from commit d3f9134aeeef784586e8412e8dbba0a8fceb0cd4) (cherry picked from commit 7afe154c5c40bcc65accdf51c9224b2f7627a684) (cherry picked from commit e6839caa4ec21e4a6d35bbc2a8ee63957263b537) (cherry picked from commit f546c95c294c4e3d828e469b8e61d7ebe1bdfeef) (cherry picked from commit 839aa964a0ab2208a3399923f8ade25978e75dcd) Conflicts: services/user/delete.go https://codeberg.org/forgejo/forgejo/pulls/1731 [MODERATION] Add repo transfers to blocked functionality (squash) - When someone gets blocked, remove all pending repository transfers from the blocked user to the doer. - Do not allow to start transferring repositories to the doer as blocked user. - Added unit testing. - Added integration testing. (cherry picked from commit 8a3caac33013482ddbee2fa51510c6918ba54466) (cherry picked from commit a92b4cfeb63b90eb2d90d0feb51cec62e0502d84) (cherry picked from commit acaaaf07d999974dbe5f9c5e792621c597bfb542) (cherry picked from commit 735818863c1793aa6f6983afedc4bd3b36026ca5) (cherry picked from commit f50fa43b32160d0d88eca1dbdca09b5f575fb62b) (cherry picked from commit e16683643388fb3c60ea478f1419a6af4f4aa283) (cherry picked from commit e0187b21fe9be69ffb3bcd2ff9262a8b241991f3) (cherry picked from commit 697a492686a070f87d953509336680e46abac479) (cherry picked from commit beb4a8a4523b6ede54fad42a6934ab69ac5613a1) [MODERATION] Fix unblock action (squash) - Pass the whole context instead of only giving pieces. - This fixes CSRF not correctly being inserted into the unblock buttons. (cherry picked from commit 2aa51922ba6a0ea2f8644277baa74fc8f34ab95a) (cherry picked from commit 7ee8db0f018340bc97f125415503e3e5db5f5082) (cherry picked from commit e4f8b999bcd3b68b3ef7f54f5b17c3ada0308121) (cherry picked from commit 05aea60b1302bbd3ea574a9c6c34e1005a5d73bf) (cherry picked from commit dc0d61b012cfaf2385f71e97cda5f220b58b9fa4) (cherry picked from commit f53fa583de671ff60a0a1d0f3ab8c260e1ba4e1f) (cherry picked from commit f3d129247ee1ade960fd2bd785bbf4bb46830e6f) (cherry picked from commit 2369d918b4f7b172af0914232fdac84ec6886aeb) (cherry picked from commit 609f56d4f277cf827f9dffe9f5d7bead4f31eefd) [MODERATION] cope with shared fixtures * There is one more issue in the fixtures and this breaks some tests * The users in the shared fixtures were renamed for clarity and that breaks some tests (cherry picked from commit 707a4edbdf67d0eb168d7bb430cf85dd8cd63c52) Conflicts: modules/indexer/issues/indexer_test.go https://codeberg.org/forgejo/forgejo/pulls/1508 (cherry picked from commit 82cc044366c749df80ffad44eed2988b8e64211e) (cherry picked from commit 2776aec7e85850f1d7f01a090a72491550fb9d29) (cherry picked from commit 1fbde36dc784b5b2cc6193f02ff0d436b0f2a629) (cherry picked from commit 1293db3c4e5df218501f5add9f9d41101ffcb8aa) (cherry picked from commit 6dbce742d3a3d3504c4e5e3f4491f1007cf50554) (cherry picked from commit 652ad8f0f77fb70930e19c82a238ca1f99e1532f) (cherry picked from commit 6ad40a59dc790213b8e7f111d0009ea2bb1dd14c) [MODERATION] Fix transfer confirmation (squash) - Fix problem caused by the clearer confirmation for dangerous actions commit. (cherry picked from commit 3488f4a9cb1f7f73103ae0017d644f13ca3ab798) (cherry picked from commit ed7de91f6ace23a1459bc6552edf719d62c7c941) (cherry picked from commit 2d97929b9b7b8d979eb12bf0994d3f169d41f7fd) (cherry picked from commit 50d035a7b058b9c4486c38cd4be0b02a4e1bf4d9) (cherry picked from commit 0a0c07d78a1dee3489b97ab359bb957e3f7fb94b) (cherry picked from commit 79009609e31f04109aa6a4074f32d02666e24e38) (cherry picked from commit b576f3cda3f10afd65ed208952e027e6033d7ee2) (cherry picked from commit c5969abfb4efa87c8f7805324763d35e47dc1fe6) [MODERATION] Purge issues on user deletion (squash) (cherry picked from commit 4f529d9596ffbfc4e754c28830ba028f6344dc5b) (cherry picked from commit f0e3acadd321fcb99e8ea3e3ce1c69df25c4ca4d) (cherry picked from commit 682c4effe69dc0d4ed304fa7ce6259d9ce573629) (cherry picked from commit eb99857433fa7e62f7430d9cf21133f7417a6a88) (cherry picked from commit 9af6e03aabde83a6078fa38390b035f388a86b51) (cherry picked from commit ad3ad4baecf24226b6f00aa1026b12fb70cb8af9) [MODERATION] Purge issues on user deletion (squash) revert shared fixtures workarounds (cherry picked from commit 7224653a40e32186892e89bfedd49edecf5b8f81) (cherry picked from commit aa6e8672f9473a9100e7575051dec9eda37709a0) (cherry picked from commit 58c7947e95648f50237ddcd46b6bd025b224a70f) (cherry picked from commit 149f6b3533190458a067a80ccdf1b3f0416ba1f8) (cherry picked from commit 65e65e04f360e5fe4e0add94eaced40627e9e241) (cherry picked from commit 57428561b55265ada37fe745d36547c99516c03a)
2023-08-15 01:07:38 +02:00 · 2023-08-15 01:07:38 +02:00 · 94b6046c52
commit 94b6046c52
parent b309d0b549
80 changed files with 2331 additions and 82 deletions
--- a/models/activities/action.go
+++ b/models/activities/action.go
@ -588,7 +588,7 @@ func NotifyWatchers(ctx context.Context, actions ...*Action) error {

 		if repoChanged {
 			// Add feeds for user self and all watchers.
-			watchers, err = repo_model.GetWatchers(ctx, act.RepoID)
+			watchers, err = repo_model.GetWatchersExcludeBlocked(ctx, act.RepoID, act.ActUserID)
 			if err != nil {
 				return fmt.Errorf("get watchers: %w", err)
 			}
--- a/models/activities/notification.go
+++ b/models/activities/notification.go
@ -235,6 +235,15 @@ func createOrUpdateIssueNotifications(ctx context.Context, issueID, commentID, n
 		for _, id := range issueUnWatches {
 			toNotify.Remove(id)
 		}
+
+		// Remove users who have the notification author blocked.
+		blockedAuthorIDs, err := user_model.ListBlockedByUsersID(ctx, notificationAuthorID)
+		if err != nil {
+			return err
+		}
+		for _, id := range blockedAuthorIDs {
+			toNotify.Remove(id)
+		}
 	}

 	err = issue.LoadRepo(ctx)
--- a/models/fixtures/comment.yml
+++ b/models/fixtures/comment.yml
@ -66,3 +66,12 @@
  tree_path: "README.md"
  created_unix: 946684812
  invalidated: true
+
+-
+  id: 8
+  type: 0 # comment
+  poster_id: 2
+  issue_id: 4 # in repo_id 2
+  content: "I just wanted to add.."
+  created_unix: 946684812
+  updated_unix: 946684812
--- a/models/fixtures/forgejo_blocked_user.yml
+++ b/models/fixtures/forgejo_blocked_user.yml
@ -0,0 +1,5 @@
+-
+  id: 1
+  user_id: 4
+  block_id: 1
+  created_unix: 1671607299
--- a/models/fixtures/issue.yml
+++ b/models/fixtures/issue.yml
@ -61,7 +61,7 @@
  priority: 0
  is_closed: true
  is_pull: false
-  num_comments: 0
+  num_comments: 1
  created_unix: 946684830
  updated_unix: 978307200
  is_locked: false
@ -338,20 +338,3 @@
  created_unix: 978307210
  updated_unix: 978307210
  is_locked: false
-
-
-  id: 21
-  repo_id: 10
-  index: 2
-  poster_id: 8
-  original_author_id: 0
-  name: issue for pr
-  content: content
-  milestone_id: 0
-  priority: 0
-  is_closed: false
-  is_pull: false
-  num_comments: 0
-  created_unix: 946684830
-  updated_unix: 978307200
-  is_locked: false
--- a/models/fixtures/issue_index.yml
+++ b/models/fixtures/issue_index.yml
@ -9,7 +9,7 @@
  max_index: 2
 -
  group_id: 10
-  max_index: 2
+  max_index: 1
 -
  group_id: 32
  max_index: 2
--- a/models/fixtures/repository.yml
+++ b/models/fixtures/repository.yml
@ -37,7 +37,7 @@
  lower_name: repo2
  name: repo2
  default_branch: master
-  num_watches: 0
+  num_watches: 1
  num_stars: 1
  num_forks: 0
  num_issues: 2
@ -83,7 +83,7 @@
  is_empty: false
  is_archived: false
  is_mirror: false
-  status: 0
+  status: 2
  is_fork: false
  fork_id: 0
  is_template: false
@ -283,7 +283,7 @@
  num_watches: 0
  num_stars: 0
  num_forks: 1
-  num_issues: 1
+  num_issues: 0
  num_closed_issues: 0
  num_pulls: 1
  num_closed_pulls: 0
--- a/models/fixtures/watch.yml
+++ b/models/fixtures/watch.yml
@ -27,3 +27,9 @@
  user_id: 11
  repo_id: 1
  mode: 3 # auto
+
+-
+  id: 6
+  user_id: 4
+  repo_id: 2
+  mode: 1 # normal
--- a/models/issues/issue_test.go
+++ b/models/issues/issue_test.go
@ -305,6 +305,8 @@ func TestIssue_ResolveMentions(t *testing.T) {
 	testSuccess("user2", "repo1", "user1", []string{"nonexisting"}, []int64{})
 	// Public repo, doer
 	testSuccess("user2", "repo1", "user1", []string{"user1"}, []int64{})
+	// Public repo, blocked user
+	testSuccess("user2", "repo1", "user1", []string{"user4"}, []int64{})
 	// Private repo, team member
 	testSuccess("org17", "big_test_private_4", "user20", []string{"user2"}, []int64{2})
 	// Private repo, not a team member
--- a/models/issues/issue_update.go
+++ b/models/issues/issue_update.go
@ -630,9 +630,11 @@ func ResolveIssueMentionsByVisibility(ctx context.Context, issue *Issue, doer *u
 				teamusers := make([]*user_model.User, 0, 20)
 				if err := db.GetEngine(ctx).
 					Join("INNER", "team_user", "team_user.uid = `user`.id").
+					Join("LEFT", "forgejo_blocked_user", "forgejo_blocked_user.user_id = `user`.id").
 					In("`team_user`.team_id", checked).
 					And("`user`.is_active = ?", true).
 					And("`user`.prohibit_login = ?", false).
+					And(builder.Or(builder.IsNull{"`forgejo_blocked_user`.block_id"}, builder.Neq{"`forgejo_blocked_user`.block_id": doer.ID})).
 					Find(&teamusers); err != nil {
 					return nil, fmt.Errorf("get teams users: %w", err)
 				}
@ -666,8 +668,10 @@ func ResolveIssueMentionsByVisibility(ctx context.Context, issue *Issue, doer *u

 	unchecked := make([]*user_model.User, 0, len(mentionUsers))
 	if err := db.GetEngine(ctx).
+		Join("LEFT", "forgejo_blocked_user", "forgejo_blocked_user.user_id = `user`.id").
 		Where("`user`.is_active = ?", true).
 		And("`user`.prohibit_login = ?", false).
+		And(builder.Or(builder.IsNull{"`forgejo_blocked_user`.block_id"}, builder.Neq{"`forgejo_blocked_user`.block_id": doer.ID})).
 		In("`user`.lower_name", mentionUsers).
 		Find(&unchecked); err != nil {
 		return nil, fmt.Errorf("find mentioned users: %w", err)
--- a/models/issues/reaction.go
+++ b/models/issues/reaction.go
@ -240,25 +240,6 @@ func CreateReaction(ctx context.Context, opts *ReactionOptions) (*Reaction, erro
 	return reaction, nil
 }

-// CreateIssueReaction creates a reaction on issue.
-func CreateIssueReaction(ctx context.Context, doerID, issueID int64, content string) (*Reaction, error) {
-	return CreateReaction(ctx, &ReactionOptions{
-		Type:    content,
-		DoerID:  doerID,
-		IssueID: issueID,
-	})
-}
-
-// CreateCommentReaction creates a reaction on comment.
-func CreateCommentReaction(ctx context.Context, doerID, issueID, commentID int64, content string) (*Reaction, error) {
-	return CreateReaction(ctx, &ReactionOptions{
-		Type:      content,
-		DoerID:    doerID,
-		IssueID:   issueID,
-		CommentID: commentID,
-	})
-}
-
 // DeleteReaction deletes reaction for issue or comment.
 func DeleteReaction(ctx context.Context, opts *ReactionOptions) error {
 	reaction := &Reaction{
--- a/models/issues/reaction_test.go
+++ b/models/issues/reaction_test.go
@ -19,11 +19,14 @@ import (
 func addReaction(t *testing.T, doerID, issueID, commentID int64, content string) {
 	var reaction *issues_model.Reaction
 	var err error
-	if commentID == 0 {
-		reaction, err = issues_model.CreateIssueReaction(db.DefaultContext, doerID, issueID, content)
-	} else {
-		reaction, err = issues_model.CreateCommentReaction(db.DefaultContext, doerID, issueID, commentID, content)
-	}
+	// NOTE: This doesn't do user blocking checking.
+	reaction, err = issues_model.CreateReaction(db.DefaultContext, &issues_model.ReactionOptions{
+		DoerID:    doerID,
+		IssueID:   issueID,
+		CommentID: commentID,
+		Type:      content,
+	})
+
 	assert.NoError(t, err)
 	assert.NotNil(t, reaction)
 }
--- a/models/repo/collaboration.go
+++ b/models/repo/collaboration.go
@ -137,6 +137,19 @@ func ChangeCollaborationAccessMode(ctx context.Context, repo *Repository, uid in
 	})
 }

+// GetCollaboratorWithUser returns all collaborator IDs of collabUserID on
+// repositories of ownerID.
+func GetCollaboratorWithUser(ctx context.Context, ownerID, collabUserID int64) ([]int64, error) {
+	collabsID := make([]int64, 0, 8)
+	err := db.GetEngine(ctx).Table("collaboration").Select("collaboration.`id`").
+		Join("INNER", "repository", "repository.id = collaboration.repo_id").
+		Where("repository.`owner_id` = ?", ownerID).
+		And("collaboration.`user_id` = ?", collabUserID).
+		Find(&collabsID)
+
+	return collabsID, err
+}
+
 // IsOwnerMemberCollaborator checks if a provided user is the owner, a collaborator or a member of a team in a repository
 func IsOwnerMemberCollaborator(ctx context.Context, repo *Repository, userID int64) (bool, error) {
 	if repo.OwnerID == userID {
--- a/models/repo/collaboration_test.go
+++ b/models/repo/collaboration_test.go
@ -11,6 +11,7 @@ import (
 	access_model "code.gitea.io/gitea/models/perm/access"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"

 	"github.com/stretchr/testify/assert"
 )
@ -156,3 +157,23 @@ func TestRepo_GetCollaboration(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Nil(t, collab)
 }
+
+func TestGetCollaboratorWithUser(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	user16 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 16})
+	user15 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 15})
+	user18 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 18})
+
+	collabs, err := repo_model.GetCollaboratorWithUser(db.DefaultContext, user16.ID, user15.ID)
+	assert.NoError(t, err)
+	assert.Len(t, collabs, 2)
+	assert.EqualValues(t, 5, collabs[0])
+	assert.EqualValues(t, 7, collabs[1])
+
+	collabs, err = repo_model.GetCollaboratorWithUser(db.DefaultContext, user16.ID, user18.ID)
+	assert.NoError(t, err)
+	assert.Len(t, collabs, 2)
+	assert.EqualValues(t, 6, collabs[0])
+	assert.EqualValues(t, 8, collabs[1])
+}
--- a/models/repo/user_repo.go
+++ b/models/repo/user_repo.go
@ -177,3 +177,16 @@ func GetIssuePostersWithSearch(ctx context.Context, repo *Repository, isPull boo
 		Limit(30).
 		Find(&users)
 }
+
+// GetWatchedRepoIDsOwnedBy returns the repos owned by a particular user watched by a particular user
+func GetWatchedRepoIDsOwnedBy(ctx context.Context, userID, ownedByUserID int64) ([]int64, error) {
+	repoIDs := make([]int64, 0, 10)
+	err := db.GetEngine(ctx).
+		Table("repository").
+		Select("`repository`.id").
+		Join("LEFT", "watch", "`repository`.id=`watch`.repo_id").
+		Where("`watch`.user_id=?", userID).
+		And("`watch`.mode<>?", WatchModeDont).
+		And("`repository`.owner_id=?", ownedByUserID).Find(&repoIDs)
+	return repoIDs, err
+}
--- a/models/repo/user_repo_test.go
+++ b/models/repo/user_repo_test.go
@ -9,6 +9,7 @@ import (
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"

 	"github.com/stretchr/testify/assert"
 )
@ -71,3 +72,15 @@ func TestRepoGetReviewers(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Len(t, reviewers, 1)
 }
+
+func GetWatchedRepoIDsOwnedBy(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	user1 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 9})
+	user2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+
+	repoIDs, err := repo_model.GetWatchedRepoIDsOwnedBy(db.DefaultContext, user1.ID, user2.ID)
+	assert.NoError(t, err)
+	assert.Len(t, repoIDs, 1)
+	assert.EqualValues(t, 1, repoIDs[0])
+}
--- a/models/repo/watch.go
+++ b/models/repo/watch.go
@ -10,6 +10,8 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/builder"
 )

 // WatchMode specifies what kind of watch the user has on a repository
@ -142,6 +144,21 @@ func GetWatchers(ctx context.Context, repoID int64) ([]*Watch, error) {
 		Find(&watches)
 }

+// GetWatchersExcludeBlocked returns all watchers of given repository, whereby
+// the doer isn't blocked by one of the watchers.
+func GetWatchersExcludeBlocked(ctx context.Context, repoID, doerID int64) ([]*Watch, error) {
+	watches := make([]*Watch, 0, 10)
+	return watches, db.GetEngine(ctx).
+		Join("INNER", "`user`", "`user`.id = `watch`.user_id").
+		Join("LEFT", "forgejo_blocked_user", "forgejo_blocked_user.user_id = `watch`.user_id").
+		Where("`watch`.repo_id=?", repoID).
+		And("`watch`.mode<>?", WatchModeDont).
+		And("`user`.is_active=?", true).
+		And("`user`.prohibit_login=?", false).
+		And(builder.Or(builder.IsNull{"`forgejo_blocked_user`.block_id"}, builder.Neq{"`forgejo_blocked_user`.block_id": doerID})).
+		Find(&watches)
+}
+
 // GetRepoWatchersIDs returns IDs of watchers for a given repo ID
 // but avoids joining with `user` for performance reasons
 // User permissions must be verified elsewhere if required
@ -184,3 +201,9 @@ func WatchIfAuto(ctx context.Context, userID, repoID int64, isWrite bool) error
 	}
 	return watchRepoMode(ctx, watch, WatchModeAuto)
 }
+
+// UnwatchRepos will unwatch the user from all given repositories.
+func UnwatchRepos(ctx context.Context, userID int64, repoIDs []int64) error {
+	_, err := db.GetEngine(ctx).Where("user_id=?", userID).In("repo_id", repoIDs).Delete(&Watch{})
+	return err
+}
--- a/models/repo/watch_test.go
+++ b/models/repo/watch_test.go
@ -43,6 +43,24 @@ func TestGetWatchers(t *testing.T) {
 	assert.Len(t, watches, 0)
 }

+func TestGetWatchersExcludeBlocked(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	watches, err := repo_model.GetWatchersExcludeBlocked(db.DefaultContext, repo.ID, 1)
+	assert.NoError(t, err)
+
+	// One watchers are inactive and one watcher is blocked, thus minus 2
+	assert.Len(t, watches, repo.NumWatches-2)
+	for _, watch := range watches {
+		assert.EqualValues(t, repo.ID, watch.RepoID)
+	}
+
+	watches, err = repo_model.GetWatchersExcludeBlocked(db.DefaultContext, unittest.NonexistentID, 1)
+	assert.NoError(t, err)
+	assert.Len(t, watches, 0)
+}
+
 func TestRepository_GetWatchers(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())

@ -137,3 +155,16 @@ func TestWatchRepoMode(t *testing.T) {
 	assert.NoError(t, repo_model.WatchRepoMode(12, 1, repo_model.WatchModeNone))
 	unittest.AssertCount(t, &repo_model.Watch{UserID: 12, RepoID: 1}, 0)
 }
+
+func TestUnwatchRepos(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	unittest.AssertExistsAndLoadBean(t, &repo_model.Watch{UserID: 4, RepoID: 1})
+	unittest.AssertExistsAndLoadBean(t, &repo_model.Watch{UserID: 4, RepoID: 2})
+
+	err := repo_model.UnwatchRepos(db.DefaultContext, 4, []int64{1, 2})
+	assert.NoError(t, err)
+
+	unittest.AssertNotExistsBean(t, &repo_model.Watch{UserID: 4, RepoID: 1})
+	unittest.AssertNotExistsBean(t, &repo_model.Watch{UserID: 4, RepoID: 2})
+}
--- a/models/repo_transfer.go
+++ b/models/repo_transfer.go
@ -417,3 +417,13 @@ func TransferOwnership(ctx context.Context, doer *user_model.User, newOwnerName

 	return committer.Commit()
 }
+
+// GetPendingTransfers returns the pending transfers of recipient which were sent by by doer.
+func GetPendingTransferIDs(ctx context.Context, reciepientID, doerID int64) ([]int64, error) {
+	pendingTransferIDs := make([]int64, 0, 8)
+	return pendingTransferIDs, db.GetEngine(ctx).Table("repo_transfer").
+		Where("doer_id = ?", doerID).
+		And("recipient_id = ?", reciepientID).
+		Cols("id").
+		Find(&pendingTransferIDs)
+}
--- a/models/repo_transfer_test.go
+++ b/models/repo_transfer_test.go
@ -55,3 +55,16 @@ func TestRepositoryTransfer(t *testing.T) {
 	// Cancel transfer
 	assert.NoError(t, CancelRepositoryTransfer(db.DefaultContext, repo))
 }
+
+func TestGetPendingTransferIDs(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 3})
+	reciepient := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	pendingTransfer := unittest.AssertExistsAndLoadBean(t, &RepoTransfer{RecipientID: reciepient.ID, DoerID: doer.ID})
+
+	pendingTransferIDs, err := GetPendingTransferIDs(db.DefaultContext, reciepient.ID, doer.ID)
+	assert.NoError(t, err)
+	if assert.Len(t, pendingTransferIDs, 1) {
+		assert.EqualValues(t, pendingTransfer.ID, pendingTransferIDs[0])
+	}
+}
--- a/models/user/block.go
+++ b/models/user/block.go
@ -0,0 +1,91 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package user
+
+import (
+	"context"
+	"errors"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// ErrBlockedByUser defines an error stating that the user is not allowed to perform the action because they are blocked.
+var ErrBlockedByUser = errors.New("user is blocked by the poster or repository owner")
+
+// BlockedUser represents a blocked user entry.
+type BlockedUser struct {
+	ID int64 `xorm:"pk autoincr"`
+	// UID of the one who got blocked.
+	BlockID int64 `xorm:"index"`
+	// UID of the one who did the block action.
+	UserID int64 `xorm:"index"`
+
+	CreatedUnix timeutil.TimeStamp `xorm:"created"`
+}
+
+// TableName provides the real table name
+func (*BlockedUser) TableName() string {
+	return "forgejo_blocked_user"
+}
+
+func init() {
+	db.RegisterModel(new(BlockedUser))
+}
+
+// IsBlocked returns if userID has blocked blockID.
+func IsBlocked(ctx context.Context, userID, blockID int64) bool {
+	has, _ := db.GetEngine(ctx).Exist(&BlockedUser{UserID: userID, BlockID: blockID})
+	return has
+}
+
+// IsBlockedMultiple returns if one of the userIDs has blocked blockID.
+func IsBlockedMultiple(ctx context.Context, userIDs []int64, blockID int64) bool {
+	has, _ := db.GetEngine(ctx).In("user_id", userIDs).Exist(&BlockedUser{BlockID: blockID})
+	return has
+}
+
+// UnblockUser removes the blocked user entry.
+func UnblockUser(ctx context.Context, userID, blockID int64) error {
+	_, err := db.GetEngine(ctx).Delete(&BlockedUser{UserID: userID, BlockID: blockID})
+	return err
+}
+
+// CountBlockedUsers returns the number of users the user has blocked.
+func CountBlockedUsers(ctx context.Context, userID int64) (int64, error) {
+	return db.GetEngine(ctx).Where("user_id=?", userID).Count(&BlockedUser{})
+}
+
+// ListBlockedUsers returns the users that the user has blocked.
+// The created_unix field of the user struct is overridden by the creation_unix
+// field of blockeduser.
+func ListBlockedUsers(ctx context.Context, userID int64, opts db.ListOptions) ([]*User, error) {
+	sess := db.GetEngine(ctx).
+		Select("`forgejo_blocked_user`.created_unix, `user`.*").
+		Join("INNER", "forgejo_blocked_user", "`user`.id=`forgejo_blocked_user`.block_id").
+		Where("`forgejo_blocked_user`.user_id=?", userID)
+
+	if opts.Page > 0 {
+		sess = db.SetSessionPagination(sess, &opts)
+		users := make([]*User, 0, opts.PageSize)
+
+		return users, sess.Find(&users)
+	}
+
+	users := make([]*User, 0, 8)
+	return users, sess.Find(&users)
+}
+
+// ListBlockedByUsersID returns the ids of the users that blocked the user.
+func ListBlockedByUsersID(ctx context.Context, userID int64) ([]int64, error) {
+	users := make([]int64, 0, 8)
+	err := db.GetEngine(ctx).
+		Table("user").
+		Select("`user`.id").
+		Join("INNER", "forgejo_blocked_user", "`user`.id=`forgejo_blocked_user`.user_id").
+		Where("`forgejo_blocked_user`.block_id=?", userID).
+		Find(&users)
+
+	return users, err
+}
--- a/models/user/block_test.go
+++ b/models/user/block_test.go
@ -0,0 +1,77 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package user_test
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsBlocked(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	assert.True(t, user_model.IsBlocked(db.DefaultContext, 4, 1))
+
+	// Simple test cases to ensure the function can also respond with false.
+	assert.False(t, user_model.IsBlocked(db.DefaultContext, 1, 1))
+	assert.False(t, user_model.IsBlocked(db.DefaultContext, 3, 2))
+}
+
+func TestIsBlockedMultiple(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	assert.True(t, user_model.IsBlockedMultiple(db.DefaultContext, []int64{4}, 1))
+	assert.True(t, user_model.IsBlockedMultiple(db.DefaultContext, []int64{4, 3, 4, 5}, 1))
+
+	// Simple test cases to ensure the function can also respond with false.
+	assert.False(t, user_model.IsBlockedMultiple(db.DefaultContext, []int64{1}, 1))
+	assert.False(t, user_model.IsBlockedMultiple(db.DefaultContext, []int64{3, 4, 1}, 2))
+}
+
+func TestUnblockUser(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	assert.True(t, user_model.IsBlocked(db.DefaultContext, 4, 1))
+
+	assert.NoError(t, user_model.UnblockUser(db.DefaultContext, 4, 1))
+
+	// Simple test cases to ensure the function can also respond with false.
+	assert.False(t, user_model.IsBlocked(db.DefaultContext, 4, 1))
+}
+
+func TestListBlockedUsers(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	blockedUsers, err := user_model.ListBlockedUsers(db.DefaultContext, 4, db.ListOptions{})
+	assert.NoError(t, err)
+	if assert.Len(t, blockedUsers, 1) {
+		assert.EqualValues(t, 1, blockedUsers[0].ID)
+		// The function returns the created Unix of the block, not that of the user.
+		assert.EqualValues(t, 1671607299, blockedUsers[0].CreatedUnix)
+	}
+}
+
+func TestListBlockedByUsersID(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	blockedByUserIDs, err := user_model.ListBlockedByUsersID(db.DefaultContext, 1)
+	assert.NoError(t, err)
+	if assert.Len(t, blockedByUserIDs, 1) {
+		assert.EqualValues(t, 4, blockedByUserIDs[0])
+	}
+}
+
+func TestCountBlockedUsers(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	count, err := user_model.CountBlockedUsers(db.DefaultContext, 4)
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, count)
+
+	count, err = user_model.CountBlockedUsers(db.DefaultContext, 1)
+	assert.NoError(t, err)
+	assert.EqualValues(t, 0, count)
+}
--- a/models/user/follow.go
+++ b/models/user/follow.go
@ -34,6 +34,10 @@ func FollowUser(ctx context.Context, userID, followID int64) (err error) {
 		return nil
 	}

+	if IsBlocked(ctx, userID, followID) || IsBlocked(ctx, followID, userID) {
+		return ErrBlockedByUser
+	}
+
 	ctx, committer, err := db.TxContext(ctx)
 	if err != nil {
 		return err
--- a/models/user/user_test.go
+++ b/models/user/user_test.go
@ -457,6 +457,12 @@ func TestFollowUser(t *testing.T) {

 	assert.NoError(t, user_model.FollowUser(db.DefaultContext, 2, 2))

+	// Blocked user.
+	assert.ErrorIs(t, user_model.ErrBlockedByUser, user_model.FollowUser(db.DefaultContext, 1, 4))
+	assert.ErrorIs(t, user_model.ErrBlockedByUser, user_model.FollowUser(db.DefaultContext, 4, 1))
+	unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: 1, FollowID: 4})
+	unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: 4, FollowID: 1})
+
 	unittest.CheckConsistencyFor(t, &user_model.User{})
 }

--- a/modules/repository/collaborator.go
+++ b/modules/repository/collaborator.go
@ -14,6 +14,10 @@ import (
 )

 func AddCollaborator(ctx context.Context, repo *repo_model.Repository, u *user_model.User) error {
+	if user_model.IsBlocked(ctx, repo.OwnerID, u.ID) || user_model.IsBlocked(ctx, u.ID, repo.OwnerID) {
+		return user_model.ErrBlockedByUser
+	}
+
 	return db.WithTx(ctx, func(ctx context.Context) error {
 		collaboration := &repo_model.Collaboration{
 			RepoID: repo.ID,
--- a/modules/repository/collaborator_test.go
+++ b/modules/repository/collaborator_test.go
@ -33,6 +33,33 @@ func TestRepository_AddCollaborator(t *testing.T) {
 	testSuccess(3, 4)
 }

+func TestRepository_AddCollaborator_IsBlocked(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	testSuccess := func(repoID, userID int64) {
+		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: repoID})
+		assert.NoError(t, repo.LoadOwner(db.DefaultContext))
+		user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: userID})
+
+		// Owner blocked user.
+		unittest.AssertSuccessfulInsert(t, &user_model.BlockedUser{UserID: repo.OwnerID, BlockID: userID})
+		assert.ErrorIs(t, AddCollaborator(db.DefaultContext, repo, user), user_model.ErrBlockedByUser)
+		unittest.CheckConsistencyFor(t, &repo_model.Repository{ID: repoID}, &user_model.User{ID: userID})
+		_, err := db.DeleteByBean(db.DefaultContext, &user_model.BlockedUser{UserID: repo.OwnerID, BlockID: userID})
+		assert.NoError(t, err)
+
+		// User has owner blocked.
+		unittest.AssertSuccessfulInsert(t, &user_model.BlockedUser{UserID: userID, BlockID: repo.OwnerID})
+		assert.ErrorIs(t, AddCollaborator(db.DefaultContext, repo, user), user_model.ErrBlockedByUser)
+		unittest.CheckConsistencyFor(t, &repo_model.Repository{ID: repoID}, &user_model.User{ID: userID})
+	}
+	// Ensure idempotency (public repository).
+	testSuccess(1, 4)
+	testSuccess(1, 4)
+	// Add collaborator to private repository.
+	testSuccess(3, 4)
+}
+
 func TestRepoPermissionPublicNonOrgRepo(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())

--- a/modules/structs/moderation.go
+++ b/modules/structs/moderation.go
@ -0,0 +1,13 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package structs
+
+import "time"
+
+// BlockedUser represents a blocked user.
+type BlockedUser struct {
+	BlockID int64 `json:"block_id"`
+	// swagger:strfmt date-time
+	Created time.Time `json:"created_at"`
+}
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@ -593,6 +593,12 @@ joined_on = Joined on %s
 repositories = Repositories
 activity = Public Activity
 followers = Followers
+block_user = Block User
+block_user.detail = Please understand that if you block this user, other actions will be taken. Such as:
+block_user.detail_1 = You are being unfollowed from this user.
+block_user.detail_2 = This user cannot interact with your repositories, created issues and comments.
+block_user.detail_3 = This user cannot add you as a collaborator, nor can you add them as a collaborator.
+follow_blocked_user = You cannot follow this user because you have blocked this user or this user has blocked you.
 starred = Starred Repositories
 watched = Watched Repositories
 code = Code
@ -601,6 +607,8 @@ overview = Overview
 following = Following
 follow = Follow
 unfollow = Unfollow
+block = Block
+unblock = Unblock
 user_bio = Biography
 disabled_public_activity = This user has disabled the public visibility of the activity.
 email_visibility.limited = Your email address is visible to all authenticated users
@ -630,6 +638,7 @@ account_link = Linked Accounts
 organization = Organizations
 uid = UID
 webauthn = Security Keys
+blocked_users = Blocked Users

 public_profile = Public Profile
 biography_placeholder = Tell us a little bit about yourself! (You can use Markdown)
@ -899,6 +908,7 @@ hooks.desc = Add webhooks which will be triggered for <strong>all repositories</

 orgs_none = You are not a member of any organizations.
 repos_none = You do not own any repositories.
+blocked_users_none = You haven't blocked any users.

 delete_account = Delete Your Account
 delete_prompt = This operation will permanently delete your user account. It <strong>CANNOT</strong> be undone.
@ -921,6 +931,10 @@ visibility.limited_tooltip = Visible only to authenticated users
 visibility.private = Private
 visibility.private_tooltip = Visible only to members of organizations you have joined

+blocked_since = Blocked since %s
+user_unblock_success = The user has been unblocked successfully.
+user_block_success = The user has been blocked successfully.
+
 [repo]
 new_repo_helper = A repository contains all project files, including revision history. Already hosting one elsewhere? <a href="%s">Migrate repository.</a>
 owner = Owner
@ -1670,6 +1684,8 @@ issues.content_history.delete_from_history = Delete from history
 issues.content_history.delete_from_history_confirm = Delete from history?
 issues.content_history.options = Options
 issues.reference_link = Reference: %s
+issues.blocked_by_user = You cannot create a issue on this repository because you are blocked by the repository owner.
+issues.comment.blocked_by_user = You cannot create a comment on this issue because you are blocked by the repository owner or the poster of the issue.

 compare.compare_base = base
 compare.compare_head = compare
@ -1749,6 +1765,7 @@ pulls.reject_count_n = "%d change requests"
 pulls.waiting_count_1 = "%d waiting review"
 pulls.waiting_count_n = "%d waiting reviews"
 pulls.wrong_commit_id = "commit id must be a commit id on the target branch"
+pulls.blocked_by_user = You cannot create a pull request on this repository because you are blocked by the repository owner.

 pulls.no_merge_desc = This pull request cannot be merged because all repository merge options are disabled.
 pulls.no_merge_helper = Enable merge options in the repository settings or merge the pull request manually.
@ -2055,6 +2072,7 @@ settings.reindex_requested=Reindex Requested
 settings.admin_enable_close_issues_via_commit_in_any_branch = Close an issue via a commit made in a non default branch
 settings.danger_zone = Danger Zone
 settings.new_owner_has_same_repo = The new owner already has a repository with same name. Please choose another name.
+settings.new_owner_blocked_doer = The new owner has blocked you.
 settings.convert = Convert to Regular Repository
 settings.convert_desc = You can convert this mirror into a regular repository. This cannot be undone.
 settings.convert_notices_1 = This operation will convert the mirror into a regular repository and cannot be undone.
@ -2113,6 +2131,8 @@ settings.add_collaborator_success = The collaborator has been added.
 settings.add_collaborator_inactive_user = Cannot add an inactive user as a collaborator.
 settings.add_collaborator_owner = Cannot add an owner as a collaborator.
 settings.add_collaborator_duplicate = The collaborator is already added to this repository.
+settings.add_collaborator_blocked_our = Cannot add the collaborator, because the repository owner has blocked them.
+settings.add_collaborator_blocked_them = Cannot add the collaborator, because they have blocked the repository owner.
 settings.delete_collaborator = Remove
 settings.collaborator_deletion = Remove Collaborator
 settings.collaborator_deletion_desc = Removing a collaborator will revoke their access to this repository. Continue?
@ -2576,6 +2596,7 @@ team_access_desc = Repository access
 team_permission_desc = Permission
 team_unit_desc = Allow Access to Repository Sections
 team_unit_disabled = (Disabled)
+follow_blocked_user = You cannot follow this organisation because this organisation has blocked you.

 form.name_reserved = The organization name "%s" is reserved.
 form.name_pattern_not_allowed = The pattern "%s" is not allowed in an organization name.
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@ -1027,6 +1027,14 @@ func Routes() *web.Route {
 					Delete(user.DeleteHook)
 			}, reqWebhooksEnabled())

+			m.Group("", func() {
+				m.Get("/list_blocked", user.ListBlockedUsers)
+				m.Group("", func() {
+					m.Put("/block/{username}", user.BlockUser)
+					m.Put("/unblock/{username}", user.UnblockUser)
+				}, context_service.UserAssignmentAPI())
+			})
+
 			m.Group("/avatar", func() {
 				m.Post("", bind(api.UpdateUserAvatarOption{}), user.UpdateAvatar)
 				m.Delete("", user.DeleteAvatar)
@ -1466,6 +1474,14 @@ func Routes() *web.Route {
 				m.Delete("", org.DeleteAvatar)
 			}, reqToken(), reqOrgOwnership())
 			m.Get("/activities/feeds", org.ListOrgActivityFeeds)
+
+			m.Group("", func() {
+				m.Get("/list_blocked", org.ListBlockedUsers)
+				m.Group("", func() {
+					m.Put("/block/{username}", org.BlockUser)
+					m.Put("/unblock/{username}", org.UnblockUser)
+				}, context_service.UserAssignmentAPI())
+			}, reqToken(), reqOrgOwnership())
 		}, tokenRequiresScopes(auth_model.AccessTokenScopeCategoryOrganization), orgAssignment(true))
 		m.Group("/teams/{teamid}", func() {
 			m.Combo("").Get(reqToken(), org.GetTeam).
--- a/routers/api/v1/org/org.go
+++ b/routers/api/v1/org/org.go
@ -5,6 +5,7 @@
 package org

 import (
+	"fmt"
 	"net/http"

 	activities_model "code.gitea.io/gitea/models/activities"
@ -457,3 +458,99 @@ func ListOrgActivityFeeds(ctx *context.APIContext) {

 	ctx.JSON(http.StatusOK, convert.ToActivities(ctx, feeds, ctx.Doer))
 }
+
+// ListBlockedUsers list the organization's blocked users.
+func ListBlockedUsers(ctx *context.APIContext) {
+	// swagger:operation GET /orgs/{org}/list_blocked organization orgListBlockedUsers
+	// ---
+	// summary: List the organization's blocked users
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: org
+	//   in: path
+	//   description: name of the org
+	//   type: string
+	//   required: true
+	// - name: page
+	//   in: query
+	//   description: page number of results to return (1-based)
+	//   type: integer
+	// - name: limit
+	//   in: query
+	//   description: page size of results
+	//   type: integer
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/BlockedUserList"
+
+	utils.ListUserBlockedUsers(ctx, ctx.ContextUser)
+}
+
+// BlockUser blocks a user from the organization.
+func BlockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /orgs/{org}/block/{username} organization orgBlockUser
+	// ---
+	// summary: Blocks a user from the organization
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: org
+	//   in: path
+	//   description: name of the org
+	//   type: string
+	//   required: true
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	if ctx.ContextUser.IsOrganization() {
+		ctx.Error(http.StatusUnprocessableEntity, "", fmt.Errorf("%s is an organization not a user", ctx.ContextUser.Name))
+		return
+	}
+
+	utils.BlockUser(ctx, ctx.Org.Organization.AsUser(), ctx.ContextUser)
+}
+
+// UnblockUser unblocks a user from the organization.
+func UnblockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /orgs/{org}/unblock/{username} organization orgUnblockUser
+	// ---
+	// summary: Unblock a user from the organization
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: org
+	//   in: path
+	//   description: name of the org
+	//   type: string
+	//   required: true
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	if ctx.ContextUser.IsOrganization() {
+		ctx.Error(http.StatusUnprocessableEntity, "", fmt.Errorf("%s is an organization not a user", ctx.ContextUser.Name))
+		return
+	}
+
+	utils.UnblockUser(ctx, ctx.Org.Organization.AsUser(), ctx.ContextUser)
+}
--- a/routers/api/v1/repo/collaborators.go
+++ b/routers/api/v1/repo/collaborators.go
@ -160,6 +160,8 @@ func AddCollaborator(ctx *context.APIContext) {
 	//     "$ref": "#/responses/notFound"
 	//   "422":
 	//     "$ref": "#/responses/validationError"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"

 	form := web.GetForm(ctx).(*api.AddCollaboratorOption)

@ -179,7 +181,11 @@ func AddCollaborator(ctx *context.APIContext) {
 	}

 	if err := repo_module.AddCollaborator(ctx, ctx.Repo.Repository, collaborator); err != nil {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "AddCollaborator", err)
+		} else {
 			ctx.Error(http.StatusInternalServerError, "AddCollaborator", err)
+		}
 		return
 	}

--- a/routers/api/v1/repo/issue.go
+++ b/routers/api/v1/repo/issue.go
@ -5,6 +5,7 @@
 package repo

 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"strconv"
@ -686,7 +687,10 @@ func CreateIssue(ctx *context.APIContext) {
 	}

 	if err := issue_service.NewIssue(ctx, ctx.Repo.Repository, issue, form.Labels, nil, assigneeIDs); err != nil {
-		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "BlockedByUser", err)
+			return
+		} else if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
 			ctx.Error(http.StatusBadRequest, "UserDoesNotHaveAccessToRepo", err)
 			return
 		}
--- a/routers/api/v1/repo/issue_comment.go
+++ b/routers/api/v1/repo/issue_comment.go
@ -378,7 +378,11 @@ func CreateIssueComment(ctx *context.APIContext) {

 	comment, err := issue_service.CreateIssueComment(ctx, ctx.Doer, ctx.Repo.Repository, issue, form.Body, nil)
 	if err != nil {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "CreateIssueComment", err)
+		} else {
 			ctx.Error(http.StatusInternalServerError, "CreateIssueComment", err)
+		}
 		return
 	}

--- a/routers/api/v1/repo/issue_reaction.go
+++ b/routers/api/v1/repo/issue_reaction.go
@ -8,11 +8,13 @@ import (
 	"net/http"

 	issues_model "code.gitea.io/gitea/models/issues"
+	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/context"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/api/v1/utils"
 	"code.gitea.io/gitea/services/convert"
+	issue_service "code.gitea.io/gitea/services/issue"
 )

 // GetIssueCommentReactions list reactions of a comment from an issue
@ -202,9 +204,9 @@ func changeIssueCommentReaction(ctx *context.APIContext, form api.EditReactionOp

 	if isCreateType {
 		// PostIssueCommentReaction part
-		reaction, err := issues_model.CreateCommentReaction(ctx, ctx.Doer.ID, comment.Issue.ID, comment.ID, form.Reaction)
+		reaction, err := issue_service.CreateCommentReaction(ctx, ctx.Doer, comment.Issue, comment, form.Reaction)
 		if err != nil {
-			if issues_model.IsErrForbiddenIssueReaction(err) {
+			if issues_model.IsErrForbiddenIssueReaction(err) || errors.Is(err, user_model.ErrBlockedByUser) {
 				ctx.Error(http.StatusForbidden, err.Error(), err)
 			} else if issues_model.IsErrReactionAlreadyExist(err) {
 				ctx.JSON(http.StatusOK, api.Reaction{
@ -418,9 +420,9 @@ func changeIssueReaction(ctx *context.APIContext, form api.EditReactionOption, i

 	if isCreateType {
 		// PostIssueReaction part
-		reaction, err := issues_model.CreateIssueReaction(ctx, ctx.Doer.ID, issue.ID, form.Reaction)
+		reaction, err := issue_service.CreateIssueReaction(ctx, ctx.Doer, issue, form.Reaction)
 		if err != nil {
-			if issues_model.IsErrForbiddenIssueReaction(err) {
+			if issues_model.IsErrForbiddenIssueReaction(err) || errors.Is(err, user_model.ErrBlockedByUser) {
 				ctx.Error(http.StatusForbidden, err.Error(), err)
 			} else if issues_model.IsErrReactionAlreadyExist(err) {
 				ctx.JSON(http.StatusOK, api.Reaction{
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@ -420,7 +420,10 @@ func CreatePullRequest(ctx *context.APIContext) {
 	}

 	if err := pull_service.NewPullRequest(ctx, repo, prIssue, labelIDs, []string{}, pr, assigneeIDs); err != nil {
-		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "BlockedByUser", err)
+			return
+		} else if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
 			ctx.Error(http.StatusBadRequest, "UserDoesNotHaveAccessToRepo", err)
 			return
 		}
--- a/routers/api/v1/repo/transfer.go
+++ b/routers/api/v1/repo/transfer.go
@ -4,6 +4,7 @@
 package repo

 import (
+	"errors"
 	"fmt"
 	"net/http"

@ -107,6 +108,11 @@ func Transfer(ctx *context.APIContext) {
 	oldFullname := ctx.Repo.Repository.FullName()

 	if err := repo_service.StartRepositoryTransfer(ctx, ctx.Doer, newOwner, ctx.Repo.Repository, teams); err != nil {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "StartRepositoryTransfer", err)
+			return
+		}
+
 		if models.IsErrRepoTransferInProgress(err) {
 			ctx.Error(http.StatusConflict, "StartRepositoryTransfer", err)
 			return
--- a/routers/api/v1/swagger/repo.go
+++ b/routers/api/v1/swagger/repo.go
@ -414,3 +414,10 @@ type swaggerRepoNewIssuePinsAllowed struct {
 	// in:body
 	Body api.NewIssuePinsAllowed `json:"body"`
 }
+
+// BlockedUserList
+// swagger:response BlockedUserList
+type swaggerBlockedUserList struct {
+	// in:body
+	Body []api.BlockedUser `json:"body"`
+}
--- a/routers/api/v1/user/follower.go
+++ b/routers/api/v1/user/follower.go
@ -5,6 +5,7 @@
 package user

 import (
+	"errors"
 	"net/http"

 	user_model "code.gitea.io/gitea/models/user"
@ -223,8 +224,14 @@ func Follow(ctx *context.APIContext) {
 	//     "$ref": "#/responses/empty"
 	//   "404":
 	//     "$ref": "#/responses/notFound"
+	//   "403":
+	//     "$ref": "#/responses/forbidden"

 	if err := user_model.FollowUser(ctx, ctx.Doer.ID, ctx.ContextUser.ID); err != nil {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Error(http.StatusForbidden, "BlockedByUser", err)
+			return
+		}
 		ctx.Error(http.StatusInternalServerError, "FollowUser", err)
 		return
 	}
--- a/routers/api/v1/user/user.go
+++ b/routers/api/v1/user/user.go
@ -5,6 +5,7 @@
 package user

 import (
+	"fmt"
 	"net/http"

 	activities_model "code.gitea.io/gitea/models/activities"
@ -202,3 +203,84 @@ func ListUserActivityFeeds(ctx *context.APIContext) {

 	ctx.JSON(http.StatusOK, convert.ToActivities(ctx, feeds, ctx.Doer))
 }
+
+// ListBlockedUsers list the authenticated user's blocked users.
+func ListBlockedUsers(ctx *context.APIContext) {
+	// swagger:operation GET /user/list_blocked user userListBlockedUsers
+	// ---
+	// summary: List the authenticated user's blocked users
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: page
+	//   in: query
+	//   description: page number of results to return (1-based)
+	//   type: integer
+	// - name: limit
+	//   in: query
+	//   description: page size of results
+	//   type: integer
+	// responses:
+	//   "200":
+	//     "$ref": "#/responses/BlockedUserList"
+
+	utils.ListUserBlockedUsers(ctx, ctx.Doer)
+}
+
+// BlockUser blocks a user from the doer.
+func BlockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /user/block/{username} user userBlockUser
+	// ---
+	// summary: Blocks a user from the doer.
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	if ctx.ContextUser.IsOrganization() {
+		ctx.Error(http.StatusUnprocessableEntity, "", fmt.Errorf("%s is an organization not a user", ctx.ContextUser.Name))
+		return
+	}
+
+	utils.BlockUser(ctx, ctx.Doer, ctx.ContextUser)
+}
+
+// UnblockUser unblocks a user from the doer.
+func UnblockUser(ctx *context.APIContext) {
+	// swagger:operation PUT /user/unblock/{username} user userUnblockUser
+	// ---
+	// summary: Unblocks a user from the doer.
+	// produces:
+	// - application/json
+	// parameters:
+	// - name: username
+	//   in: path
+	//   description: username of the user
+	//   type: string
+	//   required: true
+	// responses:
+	//   "204":
+	//     "$ref": "#/responses/empty"
+	//   "404":
+	//     "$ref": "#/responses/notFound"
+	//   "422":
+	//     "$ref": "#/responses/validationError"
+
+	if ctx.ContextUser.IsOrganization() {
+		ctx.Error(http.StatusUnprocessableEntity, "", fmt.Errorf("%s is an organization not a user", ctx.ContextUser.Name))
+		return
+	}
+
+	utils.UnblockUser(ctx, ctx.Doer, ctx.ContextUser)
+}
--- a/routers/api/v1/utils/block.go
+++ b/routers/api/v1/utils/block.go
@ -0,0 +1,65 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package utils
+
+import (
+	"net/http"
+
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/context"
+	api "code.gitea.io/gitea/modules/structs"
+	user_service "code.gitea.io/gitea/services/user"
+)
+
+// ListUserBlockedUsers lists the blocked users of the provided doer.
+func ListUserBlockedUsers(ctx *context.APIContext, doer *user_model.User) {
+	count, err := user_model.CountBlockedUsers(ctx, doer.ID)
+	if err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	blockedUsers, err := user_model.ListBlockedUsers(ctx, doer.ID, GetListOptions(ctx))
+	if err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	apiBlockedUsers := make([]*api.BlockedUser, len(blockedUsers))
+	for i, blockedUser := range blockedUsers {
+		apiBlockedUsers[i] = &api.BlockedUser{
+			BlockID: blockedUser.ID,
+			Created: blockedUser.CreatedUnix.AsTime(),
+		}
+		if err != nil {
+			ctx.InternalServerError(err)
+			return
+		}
+	}
+
+	ctx.SetTotalCountHeader(count)
+	ctx.JSON(http.StatusOK, apiBlockedUsers)
+}
+
+// BlockUser blocks the blockUser from the doer.
+func BlockUser(ctx *context.APIContext, doer, blockUser *user_model.User) {
+	err := user_service.BlockUser(ctx, doer.ID, blockUser.ID)
+	if err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
+
+// UnblockUser unblocks the blockUser from the doer.
+func UnblockUser(ctx *context.APIContext, doer, blockUser *user_model.User) {
+	err := user_model.UnblockUser(ctx, doer.ID, blockUser.ID)
+	if err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	ctx.Status(http.StatusNoContent)
+}
--- a/routers/web/org/setting/blocked_users.go
+++ b/routers/web/org/setting/blocked_users.go
@ -0,0 +1,79 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	"code.gitea.io/gitea/models/db"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/routers/utils"
+	user_service "code.gitea.io/gitea/services/user"
+)
+
+const tplBlockedUsers = "org/settings/blocked_users"
+
+// BlockedUsers renders the blocked users page.
+func BlockedUsers(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("settings.blocked_users")
+	ctx.Data["PageIsSettingsBlockedUsers"] = true
+
+	blockedUsers, err := user_model.ListBlockedUsers(ctx, ctx.Org.Organization.ID, db.ListOptions{})
+	if err != nil {
+		ctx.ServerError("ListBlockedUsers", err)
+		return
+	}
+
+	ctx.Data["BlockedUsers"] = blockedUsers
+
+	ctx.HTML(http.StatusOK, tplBlockedUsers)
+}
+
+// BlockedUsersBlock blocks a particular user from the organization.
+func BlockedUsersBlock(ctx *context.Context) {
+	uname := utils.RemoveUsernameParameterSuffix(strings.ToLower(ctx.FormString("uname")))
+	u, err := user_model.GetUserByName(ctx, uname)
+	if err != nil {
+		ctx.ServerError("GetUserByName", err)
+		return
+	}
+
+	if u.IsOrganization() {
+		ctx.ServerError("IsOrganization", fmt.Errorf("%s is an organization not a user", u.Name))
+		return
+	}
+
+	if err := user_service.BlockUser(ctx, ctx.Org.Organization.ID, u.ID); err != nil {
+		ctx.ServerError("BlockUser", err)
+		return
+	}
+
+	ctx.Flash.Success(ctx.Tr("settings.user_block_success"))
+	ctx.Redirect(ctx.Org.OrgLink + "/settings/blocked_users")
+}
+
+// BlockedUsersUnblock unblocks a particular user from the organization.
+func BlockedUsersUnblock(ctx *context.Context) {
+	u, err := user_model.GetUserByID(ctx, ctx.FormInt64("user_id"))
+	if err != nil {
+		ctx.ServerError("GetUserByID", err)
+		return
+	}
+
+	if u.IsOrganization() {
+		ctx.ServerError("IsOrganization", fmt.Errorf("%s is an organization not a user", u.Name))
+		return
+	}
+
+	if err := user_model.UnblockUser(ctx, ctx.Org.Organization.ID, u.ID); err != nil {
+		ctx.ServerError("UnblockUser", err)
+		return
+	}
+
+	ctx.Flash.Success(ctx.Tr("settings.user_unblock_success"))
+	ctx.Redirect(ctx.Org.OrgLink + "/settings/blocked_users")
+}
--- a/routers/web/repo/issue.go
+++ b/routers/web/repo/issue.go
@ -1217,7 +1217,10 @@ func NewIssuePost(ctx *context.Context) {
 	}

 	if err := issue_service.NewIssue(ctx, repo, issue, labelIDs, attachments, assigneeIDs); err != nil {
-		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.RenderWithErr(ctx.Tr("repo.issues.blocked_by_user"), tplIssueNew, form)
+			return
+		} else if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
 			ctx.Error(http.StatusBadRequest, "UserDoesNotHaveAccessToRepo", err.Error())
 			return
 		}
@ -3071,7 +3074,11 @@ func NewComment(ctx *context.Context) {

 	comment, err := issue_service.CreateIssueComment(ctx, ctx.Doer, ctx.Repo.Repository, issue, form.Content, attachments)
 	if err != nil {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Flash.Error(ctx.Tr("repo.issues.comment.blocked_by_user"))
+		} else {
 			ctx.ServerError("CreateIssueComment", err)
+		}
 		return
 	}

@ -3211,7 +3218,7 @@ func ChangeIssueReaction(ctx *context.Context) {

 	switch ctx.Params(":action") {
 	case "react":
-		reaction, err := issues_model.CreateIssueReaction(ctx, ctx.Doer.ID, issue.ID, form.Content)
+		reaction, err := issue_service.CreateIssueReaction(ctx, ctx.Doer, issue, form.Content)
 		if err != nil {
 			if issues_model.IsErrForbiddenIssueReaction(err) {
 				ctx.ServerError("ChangeIssueReaction", err)
@ -3313,7 +3320,7 @@ func ChangeCommentReaction(ctx *context.Context) {

 	switch ctx.Params(":action") {
 	case "react":
-		reaction, err := issues_model.CreateCommentReaction(ctx, ctx.Doer.ID, comment.Issue.ID, comment.ID, form.Content)
+		reaction, err := issue_service.CreateCommentReaction(ctx, ctx.Doer, comment.Issue, comment, form.Content)
 		if err != nil {
 			if issues_model.IsErrForbiddenIssueReaction(err) {
 				ctx.ServerError("ChangeIssueReaction", err)
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@ -1414,7 +1414,11 @@ func CompareAndPullRequestPost(ctx *context.Context) {
 	// instead of 500.

 	if err := pull_service.NewPullRequest(ctx, repo, pullIssue, labelIDs, attachments, pullRequest, assigneeIDs); err != nil {
-		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
+		if errors.Is(err, user_model.ErrBlockedByUser) {
+			ctx.Flash.Error(ctx.Tr("repo.pulls.blocked_by_user"))
+			ctx.Redirect(ctx.Link)
+			return
+		} else if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) {
 			ctx.Error(http.StatusBadRequest, "UserDoesNotHaveAccessToRepo", err.Error())
 			return
 		} else if git.IsErrPushRejected(err) {
--- a/routers/web/repo/setting/collaboration.go
+++ b/routers/web/repo/setting/collaboration.go
@ -4,6 +4,7 @@
 package setting

 import (
+	"errors"
 	"net/http"
 	"strings"

@ -102,10 +103,21 @@ func CollaborationPost(ctx *context.Context) {
 	}

 	if err = repo_module.AddCollaborator(ctx, ctx.Repo.Repository, u); err != nil {
+		if !errors.Is(err, user_model.ErrBlockedByUser) {
 			ctx.ServerError("AddCollaborator", err)
 			return
 		}

+		// To give an good error message, be precise on who has blocked who.
+		if blockedOurs := user_model.IsBlocked(ctx, ctx.Repo.Repository.OwnerID, u.ID); blockedOurs {
+			ctx.Flash.Error(ctx.Tr("repo.settings.add_collaborator_blocked_our"))
+		} else {
+			ctx.Flash.Error(ctx.Tr("repo.settings.add_collaborator_blocked_them"))
+		}
+		ctx.Redirect(ctx.Repo.RepoLink + "/settings/collaboration")
+		return
+	}
+
 	if setting.Service.EnableNotifyMail {
 		mailer.SendCollaboratorMail(u, ctx.Doer, ctx.Repo.Repository)
 	}
--- a/routers/web/repo/setting/setting.go
+++ b/routers/web/repo/setting/setting.go
@ -5,6 +5,7 @@
 package setting

 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"strconv"
@ -775,7 +776,9 @@ func SettingsPost(ctx *context.Context) {
 		}

 		if err := repo_service.StartRepositoryTransfer(ctx, ctx.Doer, newOwner, repo, nil); err != nil {
-			if repo_model.IsErrRepoAlreadyExist(err) {
+			if errors.Is(err, user_model.ErrBlockedByUser) {
+				ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_blocked_doer"), tplSettingsOptions, nil)
+			} else if repo_model.IsErrRepoAlreadyExist(err) {
 				ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_has_same_repo"), tplSettingsOptions, nil)
 			} else if models.IsErrRepoTransferInProgress(err) {
 				ctx.RenderWithErr(ctx.Tr("repo.settings.transfer_in_progress"), tplSettingsOptions, nil)
--- a/routers/web/repo/setting/settings_test.go
+++ b/routers/web/repo/setting/settings_test.go
@ -103,6 +103,7 @@ func TestCollaborationPost(t *testing.T) {
 	ctx.Req.Form.Set("collaborator", "user4")

 	u := &user_model.User{
+		ID:        2,
 		LowerName: "user2",
 		Type:      user_model.UserTypeIndividual,
 	}
@ -110,6 +111,7 @@ func TestCollaborationPost(t *testing.T) {
 	re := &repo_model.Repository{
 		ID:      2,
 		Owner:   u,
+		OwnerID: u.ID,
 	}

 	repo := &context.Repository{
@ -161,6 +163,7 @@ func TestCollaborationPost_AddCollaboratorTwice(t *testing.T) {
 	ctx.Req.Form.Set("collaborator", "user4")

 	u := &user_model.User{
+		ID:        2,
 		LowerName: "user2",
 		Type:      user_model.UserTypeIndividual,
 	}
@ -168,6 +171,7 @@ func TestCollaborationPost_AddCollaboratorTwice(t *testing.T) {
 	re := &repo_model.Repository{
 		ID:      2,
 		Owner:   u,
+		OwnerID: u.ID,
 	}

 	repo := &context.Repository{
--- a/routers/web/shared/user/header.go
+++ b/routers/web/shared/user/header.go
@ -31,6 +31,7 @@ func PrepareContextForProfileBigAvatar(ctx *context.Context) {
 	prepareContextForCommonProfile(ctx)

 	ctx.Data["IsFollowing"] = ctx.Doer != nil && user_model.IsFollowing(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
+	ctx.Data["IsBlocked"] = ctx.Doer != nil && user_model.IsBlocked(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
 	ctx.Data["ShowUserEmail"] = setting.UI.ShowUserEmail && ctx.ContextUser.Email != "" && ctx.IsSigned && !ctx.ContextUser.KeepEmailPrivate
 	ctx.Data["UserLocationMapURL"] = setting.Service.UserLocationMapURL

--- a/routers/web/user/profile.go
+++ b/routers/web/user/profile.go
@ -5,6 +5,7 @@
 package user

 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"strings"
@ -23,6 +24,7 @@ import (
 	"code.gitea.io/gitea/routers/web/feed"
 	"code.gitea.io/gitea/routers/web/org"
 	shared_user "code.gitea.io/gitea/routers/web/shared/user"
+	user_service "code.gitea.io/gitea/services/user"
 )

 // OwnerProfile render profile page for a user or a organization (aka, repo owner)
@ -290,17 +292,46 @@ func prepareUserProfileTabData(ctx *context.Context, showPrivate bool, profileGi
 // Action response for follow/unfollow user request
 func Action(ctx *context.Context) {
 	var err error
-	switch ctx.FormString("action") {
+	var redirectViaJSON bool
+	action := ctx.FormString("action")
+
+	if ctx.ContextUser.IsOrganization() && (action == "block" || action == "unblock") {
+		log.Error("Cannot perform this action on an organization %q", ctx.FormString("action"))
+		ctx.JSONError(fmt.Sprintf("Action %q failed", ctx.FormString("action")))
+		return
+	}
+
+	switch action {
 	case "follow":
 		err = user_model.FollowUser(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
 	case "unfollow":
 		err = user_model.UnfollowUser(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
+	case "block":
+		err = user_service.BlockUser(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
+		redirectViaJSON = true
+	case "unblock":
+		err = user_model.UnblockUser(ctx, ctx.Doer.ID, ctx.ContextUser.ID)
 	}

 	if err != nil {
+		if !errors.Is(err, user_model.ErrBlockedByUser) {
 			log.Error("Failed to apply action %q: %v", ctx.FormString("action"), err)
 			ctx.JSONError(fmt.Sprintf("Action %q failed", ctx.FormString("action")))
 			return
 		}
+
+		if ctx.ContextUser.IsOrganization() {
+			ctx.Flash.Error(ctx.Tr("org.follow_blocked_user"))
+		} else {
+			ctx.Flash.Error(ctx.Tr("user.follow_blocked_user"))
+		}
+	}
+
+	if redirectViaJSON {
+		ctx.JSON(http.StatusOK, map[string]interface{}{
+			"redirect": ctx.ContextUser.HomeLink(),
+		})
+		return
+	}
 	ctx.JSONOK()
 }
--- a/routers/web/user/setting/blocked_users.go
+++ b/routers/web/user/setting/blocked_users.go
@ -0,0 +1,46 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/models/db"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+const (
+	tplSettingsBlockedUsers base.TplName = "user/settings/blocked_users"
+)
+
+// BlockedUsers render the blocked users list page.
+func BlockedUsers(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("settings.blocked_users")
+	ctx.Data["PageIsBlockedUsers"] = true
+	ctx.Data["BaseLink"] = setting.AppSubURL + "/user/settings/blocked_users"
+	ctx.Data["BaseLinkNew"] = setting.AppSubURL + "/user/settings/blocked_users"
+
+	blockedUsers, err := user_model.ListBlockedUsers(ctx, ctx.Doer.ID, db.ListOptions{})
+	if err != nil {
+		ctx.ServerError("ListBlockedUsers", err)
+		return
+	}
+
+	ctx.Data["BlockedUsers"] = blockedUsers
+	ctx.HTML(http.StatusOK, tplSettingsBlockedUsers)
+}
+
+// UnblockUser unblocks a particular user for the doer.
+func UnblockUser(ctx *context.Context) {
+	if err := user_model.UnblockUser(ctx, ctx.Doer.ID, ctx.FormInt64("user_id")); err != nil {
+		ctx.ServerError("UnblockUser", err)
+		return
+	}
+
+	ctx.Flash.Success(ctx.Tr("settings.user_unblock_success"))
+	ctx.Redirect(setting.AppSubURL + "/user/settings/blocked_users")
+}
--- a/routers/web/web.go
+++ b/routers/web/web.go
@ -631,6 +631,11 @@ func registerRoutes(m *web.Route) {
 			})
 			addWebhookEditRoutes()
 		}, webhooksEnabled)
+
+		m.Group("/blocked_users", func() {
+			m.Get("", user_setting.BlockedUsers)
+			m.Post("/unblock", user_setting.UnblockUser)
+		})
 	}, reqSignIn, ctxDataSet("PageIsUserSettings", true, "AllThemes", setting.UI.Themes, "EnablePackages", setting.Packages.Enabled))

 	m.Group("/user", func() {
@ -888,6 +893,12 @@ func registerRoutes(m *web.Route) {

 				m.Methods("GET,POST", "/delete", org.SettingsDelete)

+				m.Group("/blocked_users", func() {
+					m.Get("", org_setting.BlockedUsers)
+					m.Post("/block", org_setting.BlockedUsersBlock)
+					m.Post("/unblock", org_setting.BlockedUsersUnblock)
+				})
+
 				m.Group("/packages", func() {
 					m.Get("", org.Packages)
 					m.Group("/rules", func() {
--- a/services/issue/comments.go
+++ b/services/issue/comments.go
@ -46,6 +46,11 @@ func CreateRefComment(ctx context.Context, doer *user_model.User, repo *repo_mod

 // CreateIssueComment creates a plain issue comment.
 func CreateIssueComment(ctx context.Context, doer *user_model.User, repo *repo_model.Repository, issue *issues_model.Issue, content string, attachments []string) (*issues_model.Comment, error) {
+	// Check if doer is blocked by the poster of the issue.
+	if user_model.IsBlocked(ctx, issue.PosterID, doer.ID) {
+		return nil, user_model.ErrBlockedByUser
+	}
+
 	comment, err := issues_model.CreateComment(ctx, &issues_model.CreateCommentOptions{
 		Type:        issues_model.CommentTypeComment,
 		Doer:        doer,
--- a/services/issue/issue.go
+++ b/services/issue/issue.go
@ -24,6 +24,11 @@ import (

 // NewIssue creates new issue with labels for repository.
 func NewIssue(ctx context.Context, repo *repo_model.Repository, issue *issues_model.Issue, labelIDs []int64, uuids []string, assigneeIDs []int64) error {
+	// Check if the user is not blocked by the repo's owner.
+	if user_model.IsBlocked(ctx, repo.OwnerID, issue.PosterID) {
+		return user_model.ErrBlockedByUser
+	}
+
 	if err := issues_model.NewIssue(ctx, repo, issue, labelIDs, uuids); err != nil {
 		return err
 	}
--- a/services/issue/reaction.go
+++ b/services/issue/reaction.go
@ -0,0 +1,47 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+package issue
+
+import (
+	"context"
+
+	issues_model "code.gitea.io/gitea/models/issues"
+	user_model "code.gitea.io/gitea/models/user"
+)
+
+// CreateIssueReaction creates a reaction on issue.
+func CreateIssueReaction(ctx context.Context, doer *user_model.User, issue *issues_model.Issue, content string) (*issues_model.Reaction, error) {
+	if err := issue.LoadRepo(ctx); err != nil {
+		return nil, err
+	}
+
+	// Check if the doer is blocked by the issue's poster or repository owner.
+	if user_model.IsBlockedMultiple(ctx, []int64{issue.PosterID, issue.Repo.OwnerID}, doer.ID) {
+		return nil, user_model.ErrBlockedByUser
+	}
+
+	return issues_model.CreateReaction(ctx, &issues_model.ReactionOptions{
+		Type:    content,
+		DoerID:  doer.ID,
+		IssueID: issue.ID,
+	})
+}
+
+// CreateCommentReaction creates a reaction on comment.
+func CreateCommentReaction(ctx context.Context, doer *user_model.User, issue *issues_model.Issue, comment *issues_model.Comment, content string) (*issues_model.Reaction, error) {
+	if err := issue.LoadRepo(ctx); err != nil {
+		return nil, err
+	}
+
+	// Check if the doer is blocked by the issue's poster, the comment's poster or repository owner.
+	if user_model.IsBlockedMultiple(ctx, []int64{comment.PosterID, issue.PosterID, issue.Repo.OwnerID}, doer.ID) {
+		return nil, user_model.ErrBlockedByUser
+	}
+
+	return issues_model.CreateReaction(ctx, &issues_model.ReactionOptions{
+		Type:      content,
+		DoerID:    doer.ID,
+		IssueID:   issue.ID,
+		CommentID: comment.ID,
+	})
+}
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@ -38,6 +38,11 @@ var pullWorkingPool = sync.NewExclusivePool()

 // NewPullRequest creates new pull request with labels for repository.
 func NewPullRequest(ctx context.Context, repo *repo_model.Repository, issue *issues_model.Issue, labelIDs []int64, uuids []string, pr *issues_model.PullRequest, assigneeIDs []int64) error {
+	// Check if the doer is not blocked by the repository's owner.
+	if user_model.IsBlocked(ctx, repo.OwnerID, issue.PosterID) {
+		return user_model.ErrBlockedByUser
+	}
+
 	prCtx, cancel, err := createTemporaryRepoForPR(ctx, pr)
 	if err != nil {
 		if !git_model.IsErrBranchNotExist(err) {
--- a/services/repository/transfer.go
+++ b/services/repository/transfer.go
@ -85,6 +85,10 @@ func ChangeRepositoryName(ctx context.Context, doer *user_model.User, repo *repo
 // StartRepositoryTransfer transfer a repo from one owner to a new one.
 // it make repository into pending transfer state, if doer can not create repo for new owner.
 func StartRepositoryTransfer(ctx context.Context, doer, newOwner *user_model.User, repo *repo_model.Repository, teams []*organization.Team) error {
+	if user_model.IsBlocked(ctx, newOwner.ID, doer.ID) {
+		return user_model.ErrBlockedByUser
+	}
+
 	if err := models.TestRepositoryReadyForTransfer(repo.Status); err != nil {
 		return err
 	}
--- a/services/repository/transfer_test.go
+++ b/services/repository/transfer_test.go
@ -63,7 +63,7 @@ func TestStartRepositoryTransferSetPermission(t *testing.T) {

 	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 3})
 	recipient := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 5})
-	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 3})
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 5})
 	repo.Owner = unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: repo.OwnerID})

 	hasAccess, err := access_model.HasAccess(db.DefaultContext, recipient.ID, repo)
--- a/services/user/block.go
+++ b/services/user/block.go
@ -0,0 +1,95 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+package user
+
+import (
+	"context"
+
+	model "code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	user_model "code.gitea.io/gitea/models/user"
+
+	"xorm.io/builder"
+)
+
+// BlockUser adds a blocked user entry for userID to block blockID.
+// TODO: Figure out if instance admins should be immune to blocking.
+// TODO: Add more mechanism like removing blocked user as collaborator on
+// repositories where the user is an owner.
+func BlockUser(ctx context.Context, userID, blockID int64) error {
+	if userID == blockID || user_model.IsBlocked(ctx, userID, blockID) {
+		return nil
+	}
+
+	ctx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return err
+	}
+	defer committer.Close()
+
+	// Add the blocked user entry.
+	_, err = db.GetEngine(ctx).Insert(&user_model.BlockedUser{UserID: userID, BlockID: blockID})
+	if err != nil {
+		return err
+	}
+
+	// Unfollow the user from the block's perspective.
+	err = user_model.UnfollowUser(ctx, blockID, userID)
+	if err != nil {
+		return err
+	}
+
+	// Unfollow the user from the doer's perspective.
+	err = user_model.UnfollowUser(ctx, userID, blockID)
+	if err != nil {
+		return err
+	}
+
+	// Blocked user unwatch all repository owned by the doer.
+	repoIDs, err := repo_model.GetWatchedRepoIDsOwnedBy(ctx, blockID, userID)
+	if err != nil {
+		return err
+	}
+
+	err = repo_model.UnwatchRepos(ctx, blockID, repoIDs)
+	if err != nil {
+		return err
+	}
+
+	// Remove blocked user as collaborator from repositories the user owns as an
+	// individual.
+	collabsID, err := repo_model.GetCollaboratorWithUser(ctx, userID, blockID)
+	if err != nil {
+		return err
+	}
+
+	_, err = db.GetEngine(ctx).In("id", collabsID).Delete(&repo_model.Collaboration{})
+	if err != nil {
+		return err
+	}
+
+	// Remove pending repository transfers, and set the status on those repository
+	// back to ready.
+	pendingTransfersIDs, err := model.GetPendingTransferIDs(ctx, userID, blockID)
+	if err != nil {
+		return err
+	}
+
+	// Use a subquery instead of a JOIN, because not every database supports JOIN
+	// on a UPDATE query.
+	_, err = db.GetEngine(ctx).Table("repository").
+		In("id", builder.Select("repo_id").From("repo_transfer").Where(builder.In("id", pendingTransfersIDs))).
+		Cols("status").
+		Update(&repo_model.Repository{Status: repo_model.RepositoryReady})
+	if err != nil {
+		return err
+	}
+
+	_, err = db.GetEngine(ctx).In("id", pendingTransfersIDs).Delete(&model.RepoTransfer{})
+	if err != nil {
+		return err
+	}
+
+	return committer.Commit()
+}
--- a/services/user/block_test.go
+++ b/services/user/block_test.go
@ -0,0 +1,91 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package user
+
+import (
+	"testing"
+
+	model "code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestBlockUser will ensure that when you block a user, certain actions have
+// been taken, like unfollowing each other etc.
+func TestBlockUser(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 5})
+	blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+
+	t.Run("Follow", func(t *testing.T) {
+		defer user_model.UnblockUser(db.DefaultContext, doer.ID, blockedUser.ID)
+
+		// Follow each other.
+		assert.NoError(t, user_model.FollowUser(db.DefaultContext, doer.ID, blockedUser.ID))
+		assert.NoError(t, user_model.FollowUser(db.DefaultContext, blockedUser.ID, doer.ID))
+
+		assert.NoError(t, BlockUser(db.DefaultContext, doer.ID, blockedUser.ID))
+
+		// Ensure they aren't following each other anymore.
+		assert.False(t, user_model.IsFollowing(db.DefaultContext, doer.ID, blockedUser.ID))
+		assert.False(t, user_model.IsFollowing(db.DefaultContext, blockedUser.ID, doer.ID))
+	})
+
+	t.Run("Watch", func(t *testing.T) {
+		defer user_model.UnblockUser(db.DefaultContext, doer.ID, blockedUser.ID)
+
+		// Blocked user watch repository of doer.
+		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{OwnerID: doer.ID})
+		assert.NoError(t, repo_model.WatchRepo(db.DefaultContext, blockedUser.ID, repo.ID, true))
+
+		assert.NoError(t, BlockUser(db.DefaultContext, doer.ID, blockedUser.ID))
+
+		// Ensure blocked user isn't following doer's repository.
+		assert.False(t, repo_model.IsWatching(db.DefaultContext, blockedUser.ID, repo.ID))
+	})
+
+	t.Run("Collaboration", func(t *testing.T) {
+		doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 16})
+		blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 18})
+		repo1 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 22, OwnerID: doer.ID})
+		repo2 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 21, OwnerID: doer.ID})
+		defer user_model.UnblockUser(db.DefaultContext, doer.ID, blockedUser.ID)
+
+		isBlockedUserCollab := func(repo *repo_model.Repository) bool {
+			isCollaborator, err := repo_model.IsCollaborator(db.DefaultContext, repo.ID, blockedUser.ID)
+			assert.NoError(t, err)
+			return isCollaborator
+		}
+
+		assert.True(t, isBlockedUserCollab(repo1))
+		assert.True(t, isBlockedUserCollab(repo2))
+
+		assert.NoError(t, BlockUser(db.DefaultContext, doer.ID, blockedUser.ID))
+
+		assert.False(t, isBlockedUserCollab(repo1))
+		assert.False(t, isBlockedUserCollab(repo2))
+	})
+
+	t.Run("Pending transfers", func(t *testing.T) {
+		doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+		blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 3})
+		defer user_model.UnblockUser(db.DefaultContext, doer.ID, blockedUser.ID)
+
+		unittest.AssertExistsIf(t, true, &repo_model.Repository{ID: 3, OwnerID: blockedUser.ID, Status: repo_model.RepositoryPendingTransfer})
+		unittest.AssertExistsIf(t, true, &model.RepoTransfer{ID: 1, RecipientID: doer.ID, DoerID: blockedUser.ID})
+
+		assert.NoError(t, BlockUser(db.DefaultContext, doer.ID, blockedUser.ID))
+
+		unittest.AssertExistsIf(t, false, &model.RepoTransfer{ID: 1, RecipientID: doer.ID, DoerID: blockedUser.ID})
+
+		// Don't use AssertExistsIf, as it doesn't include the zero values in the condition such as `repo_model.RepositoryReady`.
+		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 3, OwnerID: blockedUser.ID})
+		assert.Equal(t, repo_model.RepositoryReady, repo.Status)
+	})
+}
--- a/services/user/delete.go
+++ b/services/user/delete.go
@ -93,6 +93,8 @@ func deleteUser(ctx context.Context, u *user_model.User, purge bool) (err error)
 		&pull_model.ReviewState{UserID: u.ID},
 		&user_model.Redirect{RedirectUserID: u.ID},
 		&actions_model.ActionRunner{OwnerID: u.ID},
+		&user_model.BlockedUser{BlockID: u.ID},
+		&user_model.BlockedUser{UserID: u.ID},
 	); err != nil {
 		return fmt.Errorf("deleteBeans: %w", err)
 	}
--- a/templates/org/home.tmpl
+++ b/templates/org/home.tmpl
@ -1,5 +1,10 @@
 {{template "base/head" .}}
 <div role="main" aria-label="{{.Title}}" class="page-content organization profile">
+	{{if .Flash}}
+		<div class="ui container gt-mb-5">
+			{{template "base/alert" .}}
+		</div>
+	{{end}}
 	<div class="ui container gt-df">
 		{{ctx.AvatarUtils.Avatar .Org 140 "org-avatar"}}
 		<div id="org-info">
--- a/templates/org/settings/blocked_users.tmpl
+++ b/templates/org/settings/blocked_users.tmpl
@ -0,0 +1,21 @@
+{{template "org/settings/layout_head" (dict "ctxData" . "pageClass" "organization settings blocked-users")}}
+<div class="org-setting-content">
+	<div class="ui attached segment">
+		<form class="ui form ignore-dirty gt-df gt-fw gt-gap-3" action="{{$.Link}}/block" method="post">
+			{{.CsrfTokenHtml}}
+			<input type="hidden" name="uid" value="">
+			<div class="ui left">
+				<div id="search-user-box" class="ui search">
+					<div class="ui input">
+						<input class="prompt" name="uname" placeholder="{{.locale.Tr "repo.settings.search_user_placeholder"}}" autocomplete="off" required>
+					</div>
+				</div>
+			</div>
+			<button type="submit" class="ui red button">{{.locale.Tr "user.block"}}</button>
+		</form>
+	</div>
+	<div class="ui attached segment">
+		{{template "shared/blocked_users_list" .}}
+	</div>
+</div>
+{{template "org/settings/layout_footer" .}}
--- a/templates/org/settings/navbar.tmpl
+++ b/templates/org/settings/navbar.tmpl
@ -38,6 +38,9 @@
 			</div>
 		</details>
 		{{end}}
+			<a class="{{if .PageIsSettingsBlockedUsers}}active {{end}}item" href="{{.OrgLink}}/settings/blocked_users">
+			{{.locale.Tr "settings.blocked_users"}}
+		</a>
 		<a class="{{if .PageIsSettingsDelete}}active {{end}}item" href="{{.OrgLink}}/settings/delete">
 			{{ctx.Locale.Tr "org.settings.delete"}}
 		</a>
--- a/templates/shared/blocked_users_list.tmpl
+++ b/templates/shared/blocked_users_list.tmpl
@ -0,0 +1,28 @@
+<div class="flex-list">
+	{{range .BlockedUsers}}
+		<div class="flex-item flex-item-center">
+			<div class="flex-item-leading">
+				{{ctx.AvatarUtils.Avatar . 48}}
+			</div>
+			<div class="flex-item-main">
+				<div class="flex-item-title">
+					{{template "shared/user/name" .}}
+				</div>
+				<div class="flex-item-body">
+					<span>{{$.locale.Tr "settings.blocked_since" (DateTime "short" .CreatedUnix) | Safe}}</span>
+				</div>
+			</div>
+			<div class="flex-item-trailing">
+				<form action="{{$.Link}}/unblock" method="post">
+					{{$.CsrfTokenHtml}}
+					<input type="hidden" name="user_id" value="{{.ID}}">
+					<button class="ui red button">{{$.locale.Tr "user.unblock"}}</button>
+				</form>
+			</div>
+		</div>
+	{{else}}
+		<div class="flex-item">
+			<span class="text grey italic">{{$.locale.Tr "settings.blocked_users_none"}}</span>
+		</div>
+	{{end}}
+</div>
--- a/templates/shared/user/profile_big_avatar.tmpl
+++ b/templates/shared/user/profile_big_avatar.tmpl
@ -117,6 +117,18 @@
 					</button>
 				{{end}}
 			</li>
+			<li class="block">
+				{{if $.IsBlocked}}
+					<button class="ui basic red button link-action" data-url="{{.ContextUser.HomeLink}}?action=unblock&redirect_to={{$.Link}}">
+						{{svg "octicon-person"}} {{.locale.Tr "user.unblock"}}
+					</button>
+				{{else}}
+					<button type="submit" class="ui basic orange button delete-button"
+					data-modal-id="block-user" data-url="{{.ContextUser.HomeLink}}?action=block">
+						{{svg "octicon-blocked"}} {{.locale.Tr "user.block"}}
+					</button>
+				{{end}}
+			</li>
 			{{end}}
 		</ul>
 	</div>
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@ -1806,6 +1806,45 @@
        }
      }
    },
+    "/orgs/{org}/block/{username}": {
+      "put": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "organization"
+        ],
+        "summary": "Blocks a user from the organization",
+        "operationId": "orgBlockUser",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "name of the org",
+            "name": "org",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "username of the user",
+            "name": "username",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
    "/orgs/{org}/hooks": {
      "get": {
        "produces": [
@ -2200,6 +2239,44 @@
        }
      }
    },
+    "/orgs/{org}/list_blocked": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "organization"
+        ],
+        "summary": "List the organization's blocked users",
+        "operationId": "orgListBlockedUsers",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "name of the org",
+            "name": "org",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "description": "page number of results to return (1-based)",
+            "name": "page",
+            "in": "query"
+          },
+          {
+            "type": "integer",
+            "description": "page size of results",
+            "name": "limit",
+            "in": "query"
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/BlockedUserList"
+          }
+        }
+      }
+    },
    "/orgs/{org}/members": {
      "get": {
        "produces": [
@ -2691,6 +2768,45 @@
        }
      }
    },
+    "/orgs/{org}/unblock/{username}": {
+      "put": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "organization"
+        ],
+        "summary": "Unblock a user from the organization",
+        "operationId": "orgUnblockUser",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "name of the org",
+            "name": "org",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "username of the user",
+            "name": "username",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
    "/packages/{owner}": {
      "get": {
        "produces": [
@ -4179,6 +4295,9 @@
          "204": {
            "$ref": "#/responses/empty"
          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
          "404": {
            "$ref": "#/responses/notFound"
          },
@ -14739,6 +14858,38 @@
        }
      }
    },
+    "/user/block/{username}": {
+      "put": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "user"
+        ],
+        "summary": "Blocks a user from the doer.",
+        "operationId": "userBlockUser",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "username of the user",
+            "name": "username",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
    "/user/emails": {
      "get": {
        "produces": [
@ -14916,6 +15067,9 @@
          "204": {
            "$ref": "#/responses/empty"
          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
          "404": {
            "$ref": "#/responses/notFound"
          }
@ -15391,6 +15545,37 @@
        }
      }
    },
+    "/user/list_blocked": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "user"
+        ],
+        "summary": "List the authenticated user's blocked users",
+        "operationId": "userListBlockedUsers",
+        "parameters": [
+          {
+            "type": "integer",
+            "description": "page number of results to return (1-based)",
+            "name": "page",
+            "in": "query"
+          },
+          {
+            "type": "integer",
+            "description": "page size of results",
+            "name": "limit",
+            "in": "query"
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/BlockedUserList"
+          }
+        }
+      }
+    },
    "/user/orgs": {
      "get": {
        "produces": [
@ -15801,6 +15986,38 @@
        }
      }
    },
+    "/user/unblock/{username}": {
+      "put": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "user"
+        ],
+        "summary": "Unblocks a user from the doer.",
+        "operationId": "userUnblockUser",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "username of the user",
+            "name": "username",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          },
+          "422": {
+            "$ref": "#/responses/validationError"
+          }
+        }
+      }
+    },
    "/users/search": {
      "get": {
        "produces": [
@ -16764,6 +16981,23 @@
      },
      "x-go-package": "code.gitea.io/gitea/modules/structs"
    },
+    "BlockedUser": {
+      "type": "object",
+      "title": "BlockedUser represents a blocked user.",
+      "properties": {
+        "block_id": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "BlockID"
+        },
+        "created_at": {
+          "type": "string",
+          "format": "date-time",
+          "x-go-name": "Created"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
    "Branch": {
      "description": "Branch represents a repository branch",
      "type": "object",
@ -23084,6 +23318,15 @@
        }
      }
    },
+    "BlockedUserList": {
+      "description": "BlockedUserList",
+      "schema": {
+        "type": "array",
+        "items": {
+          "$ref": "#/definitions/BlockedUser"
+        }
+      }
+    },
    "Branch": {
      "description": "Branch",
      "schema": {
--- a/templates/user/profile.tmpl
+++ b/templates/user/profile.tmpl
@ -1,6 +1,7 @@
 {{template "base/head" .}}
 <div role="main" aria-label="{{.Title}}" class="page-content user profile">
 	<div class="ui container">
+		{{template "base/alert" .}}
 		<div class="ui stackable grid">
 			<div class="ui four wide column">
 				{{template "shared/user/profile_big_avatar" .}}
@ -39,4 +40,20 @@
 		</div>
 	</div>
 </div>
+
+<div class="ui g-modal-confirm delete modal" id="block-user">
+	<div class="header">
+		{{$.locale.Tr "user.block_user"}}
+	</div>
+	<div class="content">
+		<p>{{$.locale.Tr "user.block_user.detail"}}</p>
+		<ul>
+			<li>{{$.locale.Tr "user.block_user.detail_1"}}</li>
+			<li>{{$.locale.Tr "user.block_user.detail_2"}}</li>
+			<li>{{$.locale.Tr "user.block_user.detail_3"}}</li>
+		</ul>
+	</div>
+	{{template "base/modal_actions_confirm" .}}
+</div>
+
 {{template "base/footer" .}}
--- a/templates/user/settings/blocked_users.tmpl
+++ b/templates/user/settings/blocked_users.tmpl
@ -0,0 +1,10 @@
+{{template "user/settings/layout_head" (dict "ctxData" . "pageClass" "user settings blocked-users")}}
+<div class="user-setting-content">
+	<h4 class="ui top attached header">
+		{{.locale.Tr "settings.blocked_users"}}
+	</h4>
+	<div class="ui attached segment">
+		{{template "shared/blocked_users_list" .}}
+	</div>
+</div>
+{{template "user/settings/layout_footer" .}}
--- a/templates/user/settings/navbar.tmpl
+++ b/templates/user/settings/navbar.tmpl
@ -51,5 +51,8 @@
 		<a class="{{if .PageIsSettingsRepos}}active {{end}}item" href="{{AppSubUrl}}/user/settings/repos">
 			{{ctx.Locale.Tr "settings.repos"}}
 		</a>
+		<a class="{{if .PageIsBlockedUsers}}active {{end}}item" href="{{AppSubUrl}}/user/settings/blocked_users">
+			{{.locale.Tr "settings.blocked_users"}}
+		</a>
 	</div>
 </div>
--- a/tests/integration/admin_user_test.go
+++ b/tests/integration/admin_user_test.go
@ -4,10 +4,12 @@
 package integration

 import (
+	"fmt"
 	"net/http"
 	"strconv"
 	"testing"

+	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/tests"
@ -68,17 +70,22 @@ func makeRequest(t *testing.T, formData user_model.User, headerCode int) {
 }

 func TestAdminDeleteUser(t *testing.T) {
+	defer tests.AddFixtures("tests/integration/fixtures/TestAdminDeleteUser/")()
 	defer tests.PrepareTestEnv(t)()

 	session := loginUser(t, "user1")

-	csrf := GetCSRF(t, session, "/admin/users/8/edit")
-	req := NewRequestWithValues(t, "POST", "/admin/users/8/delete", map[string]string{
+	userID := int64(1000)
+
+	unittest.AssertExistsAndLoadBean(t, &issues_model.Issue{PosterID: userID})
+
+	csrf := GetCSRF(t, session, fmt.Sprintf("/admin/users/%d/edit", userID))
+	req := NewRequestWithValues(t, "POST", fmt.Sprintf("/admin/users/%d/delete", userID), map[string]string{
 		"_csrf": csrf,
 		"purge": "true",
 	})
 	session.MakeRequest(t, req, http.StatusSeeOther)

-	assertUserDeleted(t, 8, true)
+	assertUserDeleted(t, userID, true)
 	unittest.CheckConsistencyFor(t, &user_model.User{})
 }
--- a/tests/integration/api_block_test.go
+++ b/tests/integration/api_block_test.go
@ -0,0 +1,228 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	auth_model "code.gitea.io/gitea/models/auth"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAPIUserBlock(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	user := "user4"
+	session := loginUser(t, user)
+	token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteUser)
+
+	t.Run("BlockUser", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/user/block/user2?token=%s", token))
+		MakeRequest(t, req, http.StatusNoContent)
+
+		unittest.AssertExistsAndLoadBean(t, &user_model.BlockedUser{UserID: 4, BlockID: 2})
+	})
+
+	t.Run("ListBlocked", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/user/list_blocked?token=%s", token))
+		resp := MakeRequest(t, req, http.StatusOK)
+
+		// One user just got blocked and the other one is defined in the fixtures.
+		assert.Equal(t, "2", resp.Header().Get("X-Total-Count"))
+
+		var blockedUsers []api.BlockedUser
+		DecodeJSON(t, resp, &blockedUsers)
+		assert.Len(t, blockedUsers, 2)
+		assert.EqualValues(t, 1, blockedUsers[0].BlockID)
+		assert.EqualValues(t, 2, blockedUsers[1].BlockID)
+	})
+
+	t.Run("UnblockUser", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/user/unblock/user2?token=%s", token))
+		MakeRequest(t, req, http.StatusNoContent)
+
+		unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 4, BlockID: 2})
+	})
+
+	t.Run("Organization as target", func(t *testing.T) {
+		org := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 26, Type: user_model.UserTypeOrganization})
+
+		t.Run("Block", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/user/block/%s?token=%s", org.Name, token))
+			MakeRequest(t, req, http.StatusUnprocessableEntity)
+
+			unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 4, BlockID: org.ID})
+		})
+
+		t.Run("Unblock", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/user/unblock/%s?token=%s", org.Name, token))
+			MakeRequest(t, req, http.StatusUnprocessableEntity)
+		})
+	})
+}
+
+func TestAPIOrgBlock(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	user := "user5"
+	org := "org6"
+	session := loginUser(t, user)
+	token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteOrganization)
+
+	t.Run("BlockUser", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/block/user2?token=%s", org, token))
+		MakeRequest(t, req, http.StatusNoContent)
+
+		unittest.AssertExistsAndLoadBean(t, &user_model.BlockedUser{UserID: 6, BlockID: 2})
+	})
+
+	t.Run("ListBlocked", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/orgs/%s/list_blocked?token=%s", org, token))
+		resp := MakeRequest(t, req, http.StatusOK)
+
+		assert.Equal(t, "1", resp.Header().Get("X-Total-Count"))
+
+		var blockedUsers []api.BlockedUser
+		DecodeJSON(t, resp, &blockedUsers)
+		assert.Len(t, blockedUsers, 1)
+		assert.EqualValues(t, 2, blockedUsers[0].BlockID)
+	})
+
+	t.Run("UnblockUser", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/unblock/user2?token=%s", org, token))
+		MakeRequest(t, req, http.StatusNoContent)
+
+		unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 6, BlockID: 2})
+	})
+
+	t.Run("Organization as target", func(t *testing.T) {
+		targetOrg := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 26, Type: user_model.UserTypeOrganization})
+
+		t.Run("Block", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/block/%s?token=%s", org, targetOrg.Name, token))
+			MakeRequest(t, req, http.StatusUnprocessableEntity)
+
+			unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 4, BlockID: targetOrg.ID})
+		})
+
+		t.Run("Unblock", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/unblock/%s?token=%s", org, targetOrg.Name, token))
+			MakeRequest(t, req, http.StatusUnprocessableEntity)
+		})
+	})
+
+	t.Run("Read scope token", func(t *testing.T) {
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeReadOrganization)
+
+		t.Run("Write action", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/block/user2?token=%s", org, token))
+			MakeRequest(t, req, http.StatusForbidden)
+
+			unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 6, BlockID: 2})
+		})
+
+		t.Run("Read action", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/orgs/%s/list_blocked?token=%s", org, token))
+			MakeRequest(t, req, http.StatusOK)
+		})
+	})
+
+	t.Run("Not as owner", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		org := "org3"
+		user := "user4" // Part of org team with write perms.
+
+		session := loginUser(t, user)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteOrganization)
+
+		t.Run("Block user", func(t *testing.T) {
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/block/user2?token=%s", org, token))
+			MakeRequest(t, req, http.StatusForbidden)
+
+			unittest.AssertNotExistsBean(t, &user_model.BlockedUser{UserID: 3, BlockID: 2})
+		})
+
+		t.Run("Unblock user", func(t *testing.T) {
+			req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/orgs/%s/unblock/user2?token=%s", org, token))
+			MakeRequest(t, req, http.StatusForbidden)
+		})
+
+		t.Run("List blocked users", func(t *testing.T) {
+			req := NewRequest(t, "GET", fmt.Sprintf("/api/v1/orgs/%s/list_blocked?token=%s", org, token))
+			MakeRequest(t, req, http.StatusForbidden)
+		})
+	})
+}
+
+// TestAPIBlock_AddCollaborator ensures that the doer and blocked user cannot
+// add each others as collaborators via the API.
+func TestAPIBlock_AddCollaborator(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	user1 := "user10"
+	user2 := "user2"
+	perm := "write"
+	collabOption := &api.AddCollaboratorOption{Permission: &perm}
+
+	// User1 blocks User2.
+	session := loginUser(t, user1)
+	token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteUser, auth_model.AccessTokenScopeWriteRepository)
+
+	req := NewRequest(t, "PUT", fmt.Sprintf("/api/v1/user/block/%s?token=%s", user2, token))
+	MakeRequest(t, req, http.StatusNoContent)
+	unittest.AssertExistsAndLoadBean(t, &user_model.BlockedUser{UserID: 10, BlockID: 2})
+
+	t.Run("BlockedUser Add Doer", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2, OwnerID: 2})
+		session := loginUser(t, user2)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+
+		req := NewRequestWithJSON(t, "PUT", fmt.Sprintf("/api/v1/repos/%s/%s/collaborators/%s?token=%s", user2, repo.Name, user1, token), collabOption)
+		session.MakeRequest(t, req, http.StatusForbidden)
+	})
+
+	t.Run("Doer Add BlockedUser", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 7, OwnerID: 10})
+		session := loginUser(t, user1)
+		token := getTokenForLoggedInUser(t, session, auth_model.AccessTokenScopeWriteRepository)
+
+		req := NewRequestWithJSON(t, "PUT", fmt.Sprintf("/api/v1/repos/%s/%s/collaborators/%s?token=%s", user1, repo.Name, user2, token), collabOption)
+		session.MakeRequest(t, req, http.StatusForbidden)
+	})
+}
--- a/tests/integration/api_issue_test.go
+++ b/tests/integration/api_issue_test.go
@ -370,7 +370,7 @@ func TestAPISearchIssues(t *testing.T) {
 	token := getUserToken(t, "user2", auth_model.AccessTokenScopeReadIssue)

 	// as this API was used in the frontend, it uses UI page size
-	expectedIssueCount := 19 // from the fixtures
+	expectedIssueCount := 18 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
@ -394,7 +394,7 @@ func TestAPISearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 12)
+	assert.Len(t, apiIssues, 11)
 	query.Del("since")
 	query.Del("before")

@ -410,15 +410,15 @@ func TestAPISearchIssues(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "21", resp.Header().Get("X-Total-Count"))
-	assert.Len(t, apiIssues, 21)
+	assert.EqualValues(t, "20", resp.Header().Get("X-Total-Count"))
+	assert.Len(t, apiIssues, 20)

 	query.Add("limit", "10")
 	link.RawQuery = query.Encode()
 	req = NewRequest(t, "GET", link.String())
 	resp = MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.EqualValues(t, "21", resp.Header().Get("X-Total-Count"))
+	assert.EqualValues(t, "20", resp.Header().Get("X-Total-Count"))
 	assert.Len(t, apiIssues, 10)

 	query = url.Values{"assigned": {"true"}, "state": {"all"}, "token": {token}}
@ -468,7 +468,7 @@ func TestAPISearchIssuesWithLabels(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()

 	// as this API was used in the frontend, it uses UI page size
-	expectedIssueCount := 19 // from the fixtures
+	expectedIssueCount := 18 // from the fixtures
 	if expectedIssueCount > setting.UI.IssuePagingNum {
 		expectedIssueCount = setting.UI.IssuePagingNum
 	}
--- a/tests/integration/api_nodeinfo_test.go
+++ b/tests/integration/api_nodeinfo_test.go
@ -33,7 +33,7 @@ func TestNodeinfo(t *testing.T) {
 		assert.True(t, nodeinfo.OpenRegistrations)
 		assert.Equal(t, "gitea", nodeinfo.Software.Name)
 		assert.Equal(t, 25, nodeinfo.Usage.Users.Total)
-		assert.Equal(t, 21, nodeinfo.Usage.LocalPosts)
-		assert.Equal(t, 2, nodeinfo.Usage.LocalComments)
+		assert.Equal(t, 20, nodeinfo.Usage.LocalPosts)
+		assert.Equal(t, 3, nodeinfo.Usage.LocalComments)
 	})
 }
--- a/tests/integration/api_user_follow_test.go
+++ b/tests/integration/api_user_follow_test.go
@ -19,7 +19,7 @@ func TestAPIFollow(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()

 	user1 := "user4"
-	user2 := "user1"
+	user2 := "user10"

 	session1 := loginUser(t, user1)
 	token1 := getTokenForLoggedInUser(t, session1, auth_model.AccessTokenScopeReadUser)
--- a/tests/integration/block_test.go
+++ b/tests/integration/block_test.go
@ -0,0 +1,388 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+	"strconv"
+	"testing"
+
+	issue_model "code.gitea.io/gitea/models/issues"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	forgejo_context "code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/translation"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func BlockUser(t *testing.T, doer, blockedUser *user_model.User) {
+	t.Helper()
+
+	unittest.AssertNotExistsBean(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: doer.ID})
+
+	session := loginUser(t, doer.Name)
+	req := NewRequestWithValues(t, "POST", "/"+blockedUser.Name, map[string]string{
+		"_csrf":  GetCSRF(t, session, "/"+blockedUser.Name),
+		"action": "block",
+	})
+	resp := session.MakeRequest(t, req, http.StatusOK)
+
+	type redirect struct {
+		Redirect string `json:"redirect"`
+	}
+
+	var respBody redirect
+	DecodeJSON(t, resp, &respBody)
+	assert.EqualValues(t, "/"+blockedUser.Name, respBody.Redirect)
+	assert.True(t, unittest.BeanExists(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: doer.ID}))
+}
+
+// TestBlockUser ensures that users can execute blocking related actions can
+// happen under the correct conditions.
+func TestBlockUser(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 8})
+	blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	session := loginUser(t, doer.Name)
+
+	t.Run("Block", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		BlockUser(t, doer, blockedUser)
+	})
+
+	// Unblock user.
+	t.Run("Unblock", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		req := NewRequestWithValues(t, "POST", "/"+blockedUser.Name, map[string]string{
+			"_csrf":  GetCSRF(t, session, "/"+blockedUser.Name),
+			"action": "unblock",
+		})
+		session.MakeRequest(t, req, http.StatusOK)
+
+		unittest.AssertNotExistsBean(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: doer.ID})
+	})
+
+	t.Run("Organization as target", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+		targetOrg := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 3, Type: user_model.UserTypeOrganization})
+
+		t.Run("Block", func(t *testing.T) {
+			req := NewRequestWithValues(t, "POST", "/"+targetOrg.Name, map[string]string{
+				"_csrf":  GetCSRF(t, session, "/"+targetOrg.Name),
+				"action": "block",
+			})
+			resp := session.MakeRequest(t, req, http.StatusBadRequest)
+
+			assert.Contains(t, resp.Body.String(), "Action \\\"block\\\" failed")
+		})
+
+		t.Run("Unblock", func(t *testing.T) {
+			req := NewRequestWithValues(t, "POST", "/"+targetOrg.Name, map[string]string{
+				"_csrf":  GetCSRF(t, session, "/"+targetOrg.Name),
+				"action": "unblock",
+			})
+			resp := session.MakeRequest(t, req, http.StatusBadRequest)
+
+			assert.Contains(t, resp.Body.String(), "Action \\\"unblock\\\" failed")
+		})
+	})
+}
+
+// TestBlockUserFromOrganization ensures that an organisation can block and unblock an user.
+func TestBlockUserFromOrganization(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 15})
+	blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	org := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 17, Type: user_model.UserTypeOrganization})
+	unittest.AssertNotExistsBean(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: org.ID})
+	session := loginUser(t, doer.Name)
+
+	t.Run("Block user", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequestWithValues(t, "POST", org.OrganisationLink()+"/settings/blocked_users/block", map[string]string{
+			"_csrf": GetCSRF(t, session, org.OrganisationLink()+"/settings/blocked_users"),
+			"uname": blockedUser.Name,
+		})
+		session.MakeRequest(t, req, http.StatusSeeOther)
+		assert.True(t, unittest.BeanExists(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: org.ID}))
+	})
+
+	t.Run("Unblock user", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequestWithValues(t, "POST", org.OrganisationLink()+"/settings/blocked_users/unblock", map[string]string{
+			"_csrf":   GetCSRF(t, session, org.OrganisationLink()+"/settings/blocked_users"),
+			"user_id": strconv.FormatInt(blockedUser.ID, 10),
+		})
+		session.MakeRequest(t, req, http.StatusSeeOther)
+		unittest.AssertNotExistsBean(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: org.ID})
+	})
+
+	t.Run("Organization as target", func(t *testing.T) {
+		targetOrg := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 3, Type: user_model.UserTypeOrganization})
+
+		t.Run("Block", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequestWithValues(t, "POST", org.OrganisationLink()+"/settings/blocked_users/block", map[string]string{
+				"_csrf": GetCSRF(t, session, org.OrganisationLink()+"/settings/blocked_users"),
+				"uname": targetOrg.Name,
+			})
+			session.MakeRequest(t, req, http.StatusInternalServerError)
+			unittest.AssertNotExistsBean(t, &user_model.BlockedUser{BlockID: blockedUser.ID, UserID: targetOrg.ID})
+		})
+
+		t.Run("Unblock", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequestWithValues(t, "POST", org.OrganisationLink()+"/settings/blocked_users/unblock", map[string]string{
+				"_csrf":   GetCSRF(t, session, org.OrganisationLink()+"/settings/blocked_users"),
+				"user_id": strconv.FormatInt(targetOrg.ID, 10),
+			})
+			session.MakeRequest(t, req, http.StatusInternalServerError)
+		})
+	})
+}
+
+// TestBlockActions ensures that certain actions cannot be performed as a doer
+// and as a blocked user and are handled cleanly after the blocking has taken
+// place.
+func TestBlockActions(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	doer := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+	blockedUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	blockedUser2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 10})
+	repo2 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2, OwnerID: doer.ID})
+	repo7 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 7, OwnerID: blockedUser2.ID})
+	issue4 := unittest.AssertExistsAndLoadBean(t, &issue_model.Issue{ID: 4, RepoID: repo2.ID})
+	issue4URL := fmt.Sprintf("/%s/issues/%d", repo2.FullName(), issue4.Index)
+	// NOTE: Sessions shouldn't be shared, because in some situations flash
+	// messages are persistent and that would interfere with accurate test
+	// results.
+
+	BlockUser(t, doer, blockedUser)
+	BlockUser(t, doer, blockedUser2)
+
+	// Ensures that issue creation on doer's ownen repositories are blocked.
+	t.Run("Issue creation", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		session := loginUser(t, blockedUser.Name)
+		link := fmt.Sprintf("%s/issues/new", repo2.FullName())
+
+		req := NewRequestWithValues(t, "POST", link, map[string]string{
+			"_csrf":   GetCSRF(t, session, link),
+			"title":   "Title",
+			"content": "Hello!",
+		})
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		htmlDoc := NewHTMLParser(t, resp.Body)
+		assert.Contains(t,
+			htmlDoc.doc.Find(".ui.negative.message").Text(),
+			translation.NewLocale("en-US").Tr("repo.issues.blocked_by_user"),
+		)
+	})
+
+	// Ensures that comment creation on doer's owned repositories and doer's
+	// posted issues are blocked.
+	t.Run("Comment creation", func(t *testing.T) {
+		expectedFlash := "error%3DYou%2Bcannot%2Bcreate%2Ba%2Bcomment%2Bon%2Bthis%2Bissue%2Bbecause%2Byou%2Bare%2Bblocked%2Bby%2Bthe%2Brepository%2Bowner%2Bor%2Bthe%2Bposter%2Bof%2Bthe%2Bissue."
+
+		t.Run("Blocked by repository owner", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, blockedUser.Name)
+
+			req := NewRequestWithValues(t, "POST", path.Join(issue4URL, "/comments"), map[string]string{
+				"_csrf":   GetCSRF(t, session, issue4URL),
+				"content": "Not a kind comment",
+			})
+			session.MakeRequest(t, req, http.StatusOK)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, expectedFlash, flashCookie.Value)
+		})
+
+		t.Run("Blocked by issue poster", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			repo5 := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 5})
+			issue15 := unittest.AssertExistsAndLoadBean(t, &issue_model.Issue{ID: 15, RepoID: repo5.ID, PosterID: doer.ID})
+
+			session := loginUser(t, blockedUser.Name)
+			issueURL := fmt.Sprintf("/%s/%s/issues/%d", url.PathEscape(repo5.OwnerName), url.PathEscape(repo5.Name), issue15.Index)
+
+			req := NewRequestWithValues(t, "POST", path.Join(issueURL, "/comments"), map[string]string{
+				"_csrf":   GetCSRF(t, session, issueURL),
+				"content": "Not a kind comment",
+			})
+			session.MakeRequest(t, req, http.StatusOK)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, expectedFlash, flashCookie.Value)
+		})
+	})
+
+	// Ensures that reactions on doer's owned issues and doer's owned comments are
+	// blocked.
+	t.Run("Add a reaction", func(t *testing.T) {
+		type reactionResponse struct {
+			Empty bool `json:"empty"`
+		}
+
+		t.Run("On a issue", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, blockedUser.Name)
+
+			req := NewRequestWithValues(t, "POST", path.Join(issue4URL, "/reactions/react"), map[string]string{
+				"_csrf":   GetCSRF(t, session, issue4URL),
+				"content": "eyes",
+			})
+			resp := session.MakeRequest(t, req, http.StatusOK)
+
+			var respBody reactionResponse
+			DecodeJSON(t, resp, &respBody)
+
+			assert.EqualValues(t, true, respBody.Empty)
+		})
+
+		t.Run("On a comment", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			comment := unittest.AssertExistsAndLoadBean(t, &issue_model.Comment{ID: 8, PosterID: doer.ID, IssueID: issue4.ID})
+
+			session := loginUser(t, blockedUser.Name)
+
+			req := NewRequestWithValues(t, "POST", fmt.Sprintf("%s/comments/%d/reactions/react", repo2.FullName(), comment.ID), map[string]string{
+				"_csrf":   GetCSRF(t, session, issue4URL),
+				"content": "eyes",
+			})
+			resp := session.MakeRequest(t, req, http.StatusOK)
+
+			var respBody reactionResponse
+			DecodeJSON(t, resp, &respBody)
+
+			assert.EqualValues(t, true, respBody.Empty)
+		})
+	})
+
+	// Ensures that the doer and blocked user cannot follow each other.
+	t.Run("Follow", func(t *testing.T) {
+		// Sanity checks to make sure doing these tests are valid.
+		unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: doer.ID, FollowID: blockedUser.ID})
+		unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: blockedUser.ID, FollowID: doer.ID})
+
+		// Doer cannot follow blocked user.
+		t.Run("Doer follow blocked user", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, doer.Name)
+
+			req := NewRequestWithValues(t, "POST", "/"+blockedUser.Name, map[string]string{
+				"_csrf":  GetCSRF(t, session, "/"+blockedUser.Name),
+				"action": "follow",
+			})
+			session.MakeRequest(t, req, http.StatusOK)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, "error%3DYou%2Bcannot%2Bfollow%2Bthis%2Buser%2Bbecause%2Byou%2Bhave%2Bblocked%2Bthis%2Buser%2Bor%2Bthis%2Buser%2Bhas%2Bblocked%2Byou.", flashCookie.Value)
+
+			// Assert it still doesn't exist.
+			unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: doer.ID, FollowID: blockedUser.ID})
+		})
+
+		// Blocked user cannot follow doer.
+		t.Run("Blocked user follow doer", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, blockedUser.Name)
+
+			req := NewRequestWithValues(t, "POST", "/"+doer.Name, map[string]string{
+				"_csrf":  GetCSRF(t, session, "/"+doer.Name),
+				"action": "follow",
+			})
+			session.MakeRequest(t, req, http.StatusOK)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, "error%3DYou%2Bcannot%2Bfollow%2Bthis%2Buser%2Bbecause%2Byou%2Bhave%2Bblocked%2Bthis%2Buser%2Bor%2Bthis%2Buser%2Bhas%2Bblocked%2Byou.", flashCookie.Value)
+
+			unittest.AssertNotExistsBean(t, &user_model.Follow{UserID: blockedUser.ID, FollowID: doer.ID})
+		})
+	})
+
+	// Ensures that the doer and blocked user cannot add each each other as collaborators.
+	t.Run("Add collaborator", func(t *testing.T) {
+		t.Run("Doer Add BlockedUser", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, doer.Name)
+			link := fmt.Sprintf("/%s/settings/collaboration", repo2.FullName())
+
+			req := NewRequestWithValues(t, "POST", link, map[string]string{
+				"_csrf":        GetCSRF(t, session, link),
+				"collaborator": blockedUser2.Name,
+			})
+			session.MakeRequest(t, req, http.StatusSeeOther)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, "error%3DCannot%2Badd%2Bthe%2Bcollaborator%252C%2Bbecause%2Bthe%2Brepository%2Bowner%2Bhas%2Bblocked%2Bthem.", flashCookie.Value)
+		})
+
+		t.Run("BlockedUser Add doer", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			session := loginUser(t, blockedUser2.Name)
+			link := fmt.Sprintf("/%s/settings/collaboration", repo7.FullName())
+
+			req := NewRequestWithValues(t, "POST", link, map[string]string{
+				"_csrf":        GetCSRF(t, session, link),
+				"collaborator": doer.Name,
+			})
+			session.MakeRequest(t, req, http.StatusSeeOther)
+
+			flashCookie := session.GetCookie(forgejo_context.CookieNameFlash)
+			assert.NotNil(t, flashCookie)
+			assert.EqualValues(t, "error%3DCannot%2Badd%2Bthe%2Bcollaborator%252C%2Bbecause%2Bthey%2Bhave%2Bblocked%2Bthe%2Brepository%2Bowner.", flashCookie.Value)
+		})
+	})
+
+	// Ensures that the blocked user cannot transfer a repository to the doer.
+	t.Run("Repository transfer", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		session := loginUser(t, blockedUser2.Name)
+		link := fmt.Sprintf("%s/settings", repo7.FullName())
+
+		req := NewRequestWithValues(t, "POST", link, map[string]string{
+			"_csrf":          GetCSRF(t, session, link),
+			"action":         "transfer",
+			"repo_name":      repo7.FullName(),
+			"new_owner_name": doer.Name,
+		})
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		htmlDoc := NewHTMLParser(t, resp.Body)
+		assert.Contains(t,
+			htmlDoc.doc.Find(".ui.negative.message").Text(),
+			translation.NewLocale("en-US").Tr("repo.settings.new_owner_blocked_doer"),
+		)
+	})
+}
--- a/tests/integration/fixtures/TestAdminDeleteUser/issue.yml
+++ b/tests/integration/fixtures/TestAdminDeleteUser/issue.yml
@ -0,0 +1,16 @@
+-
+  id: 1000
+  repo_id: 1000
+  index: 2
+  poster_id: 1000
+  original_author_id: 0
+  name: NAME
+  content: content
+  milestone_id: 0
+  priority: 0
+  is_closed: false
+  is_pull: false
+  num_comments: 0
+  created_unix: 946684830
+  updated_unix: 978307200
+  is_locked: false
--- a/tests/integration/fixtures/TestAdminDeleteUser/issue_index.yml
+++ b/tests/integration/fixtures/TestAdminDeleteUser/issue_index.yml
@ -0,0 +1,3 @@
+-
+  group_id: 1000
+  max_index: 2
--- a/tests/integration/fixtures/TestAdminDeleteUser/repository.yml
+++ b/tests/integration/fixtures/TestAdminDeleteUser/repository.yml
@ -0,0 +1,30 @@
+-
+  id: 1000
+  owner_id: 1001
+  owner_name: user1001
+  lower_name: repo1000
+  name: repo1000
+  default_branch: master
+  num_watches: 0
+  num_stars: 0
+  num_forks: 0
+  num_issues: 1
+  num_closed_issues: 0
+  num_pulls: 0
+  num_closed_pulls: 0
+  num_milestones: 0
+  num_closed_milestones: 0
+  num_projects: 0
+  num_closed_projects: 0
+  is_private: false
+  is_empty: false
+  is_archived: false
+  is_mirror: false
+  status: 0
+  is_fork: false
+  fork_id: 0
+  is_template: false
+  template_id: 0
+  size: 0
+  is_fsck_enabled: true
+  close_issues_via_commit_in_any_branch: false
--- a/tests/integration/fixtures/TestAdminDeleteUser/user.yml
+++ b/tests/integration/fixtures/TestAdminDeleteUser/user.yml
@ -0,0 +1,73 @@
+-
+  id: 1000
+  lower_name: user1000
+  name: user1000
+  full_name: User Thousand
+  email: user1000@example.com
+  keep_email_private: false
+  email_notifications_preference: enabled
+  passwd: ZogKvWdyEx:password
+  passwd_hash_algo: dummy
+  must_change_password: false
+  login_source: 0
+  login_name: user1000
+  type: 0
+  salt: ZogKvWdyEx
+  max_repo_creation: -1
+  is_active: true
+  is_admin: false
+  is_restricted: false
+  allow_git_hook: false
+  allow_import_local: false
+  allow_create_organization: true
+  prohibit_login: false
+  avatar: avatar1000
+  avatar_email: user1000@example.com
+  use_custom_avatar: false
+  num_followers: 1
+  num_following: 1
+  num_stars: 0
+  num_repos: 0
+  num_teams: 0
+  num_members: 0
+  visibility: 0
+  repo_admin_change_team_access: false
+  theme: ""
+  keep_activity_private: false
+
+-
+  id: 1001
+  lower_name: user1001
+  name: user1001
+  full_name: User 1001
+  email: user1001@example.com
+  keep_email_private: false
+  email_notifications_preference: enabled
+  passwd: ZogKvWdyEx:password
+  passwd_hash_algo: dummy
+  must_change_password: false
+  login_source: 0
+  login_name: user1001
+  type: 0
+  salt: ZogKvWdyEx
+  max_repo_creation: -1
+  is_active: true
+  is_admin: false
+  is_restricted: false
+  allow_git_hook: false
+  allow_import_local: false
+  allow_create_organization: true
+  prohibit_login: false
+  avatar: avatar1001
+  avatar_email: user1001@example.com
+  use_custom_avatar: false
+  num_followers: 0
+  num_following: 0
+  num_stars: 0
+  num_repos: 1
+  num_teams: 0
+  num_members: 0
+  visibility: 0
+  repo_admin_change_team_access: false
+  theme: ""
+  keep_activity_private: false
--- a/web_src/css/org.css
+++ b/web_src/css/org.css
@ -166,6 +166,22 @@
  border-bottom: 1px solid var(--color-secondary);
 }

+.organization.teams .repositories .item,
+.organization.teams .members .item {
+  padding: 10px 19px;
+}
+
+.organization.teams .repositories .item:not(:last-child),
+.organization.teams .members .item:not(:last-child) {
+  border-bottom: 1px solid var(--color-secondary);
+}
+
+.organization.teams .repositories .item .button,
+.organization.teams .members .item .button {
+  padding: 9px 10px;
+  margin: 0;
+}
+
 .org-team-navbar .active.item {
  background: var(--color-box-body) !important;
 }
--- a/web_src/css/user.css
+++ b/web_src/css/user.css
@ -36,6 +36,19 @@
  width: 100%;
 }

+.user.profile .ui.card .extra.content > ul > li .svg {
+  margin-left: 1px;
+  margin-right: 5px;
+}
+
+.user.profile .ui.card .extra.content > ul > li.follow .ui.button,
+.user.profile .ui.card .extra.content > ul > li.block .ui.button {
+  align-items: center;
+  display: flex;
+  justify-content: center;
+  width: 100%;
+}
+
 .user.profile .ui.card #profile-avatar {
  padding: 1rem 1rem 0.25rem;
  justify-content: center;