diff --git a/Makefile b/Makefile
index 178569d2e..c1683da2e 100644
--- a/Makefile
+++ b/Makefile
@@ -92,7 +92,10 @@ else
 endif
 VERSION = ${GITEA_VERSION}
 
-LDFLAGS := $(LDFLAGS) -X "main.MakeVersion=$(MAKE_VERSION)" -X "main.Version=$(GITEA_VERSION)" -X "main.Tags=$(TAGS)"
+# SemVer
+FORGEJO_VERSION := 5.0.0+0-gitea-1.20.0
+
+LDFLAGS := $(LDFLAGS) -X "main.MakeVersion=$(MAKE_VERSION)" -X "main.Version=$(GITEA_VERSION)" -X "main.Tags=$(TAGS)" -X "code.gitea.io/gitea/routers/api/forgejo/v1.ForgejoVersion=$(FORGEJO_VERSION)"
 
 LINUX_ARCHS ?= linux/amd64,linux/386,linux/arm-5,linux/arm-6,linux/arm64
 
@@ -144,6 +147,8 @@ ifdef DEPS_PLAYWRIGHT
 	PLAYWRIGHT_FLAGS += --with-deps
 endif
 
+FORGEJO_API_SPEC := public/assets/forgejo/api.v1.yml
+
 SWAGGER_SPEC := templates/swagger/v1_json.tmpl
 SWAGGER_SPEC_S_TMPL := s|"basePath": *"/api/v1"|"basePath": "{{AppSubUrl \| JSEscape \| Safe}}/api/v1"|g
 SWAGGER_SPEC_S_JSON := s|"basePath": *"{{AppSubUrl \| JSEscape \| Safe}}/api/v1"|"basePath": "/api/v1"|g
@@ -220,6 +225,8 @@ help:
 	@echo " - generate-license                 update license files"
 	@echo " - generate-gitignore               update gitignore files"
 	@echo " - generate-manpage                 generate manpage"
+	@echo " - generate-forgejo-api             generate the forgejo API from spec"
+	@echo " - forgejo-api-validate             check if the forgejo API matches the specs"
 	@echo " - generate-swagger                 generate the swagger spec from code comments"
 	@echo " - swagger-validate                 check if the swagger spec is valid"
 	@echo " - go-licenses                      regenerate go licenses"
@@ -304,6 +311,27 @@ ifneq "$(TAGS)" "$(shell cat $(TAGS_EVIDENCE) 2>/dev/null)"
 TAGS_PREREQ := $(TAGS_EVIDENCE)
 endif
 
+OAPI_CODEGEN_PACKAGE ?= github.com/deepmap/oapi-codegen/cmd/oapi-codegen@v1.12.4
+KIN_OPENAPI_CODEGEN_PACKAGE ?= github.com/getkin/kin-openapi/cmd/validate@v0.114.0
+FORGEJO_API_SERVER = routers/api/forgejo/v1/generated.go
+
+.PHONY: generate-forgejo-api
+generate-forgejo-api: $(FORGEJO_API_SPEC)
+	$(GO) run $(OAPI_CODEGEN_PACKAGE) -package v1 -generate chi-server,types $< > $(FORGEJO_API_SERVER)
+
+.PHONY: forgejo-api-check
+forgejo-api-check: generate-forgejo-api
+	@diff=$$(git diff $(FORGEJO_API_SERVER) ; \
+	if [ -n "$$diff" ]; then \
+		echo "Please run 'make generate-forgejo-api' and commit the result:"; \
+		echo "$${diff}"; \
+		exit 1; \
+	fi
+
+.PHONY: forgejo-api-validate
+forgejo-api-validate:
+	$(GO) run $(KIN_OPENAPI_CODEGEN_PACKAGE) $(FORGEJO_API_SPEC)
+
 .PHONY: generate-swagger
 generate-swagger: $(SWAGGER_SPEC)
 
@@ -334,7 +362,7 @@ checks: checks-frontend checks-backend
 checks-frontend: lockfile-check svg-check
 
 .PHONY: checks-backend
-checks-backend: tidy-check swagger-check fmt-check misspell-check swagger-validate security-check
+checks-backend: tidy-check swagger-check fmt-check misspell-check forgejo-api-validate swagger-validate security-check
 
 .PHONY: lint
 lint: lint-frontend lint-backend
diff --git a/public/assets/forgejo/api.v1.yml b/public/assets/forgejo/api.v1.yml
new file mode 100644
index 000000000..924ea91d7
--- /dev/null
+++ b/public/assets/forgejo/api.v1.yml
@@ -0,0 +1,40 @@
+openapi: 3.0.0
+info:
+  title: Forgejo API
+  description: |-
+    Forgejo REST API
+
+  contact:
+    email: contact@forgejo.org
+  license:
+    name: MIT
+    url: https://codeberg.org/forgejo/forgejo/src/branch/forgejo/LICENSE
+  version: 1.0.0
+externalDocs:
+  description: Find out more about Forgejo
+  url: http://forgejo.org
+servers:
+  - url: /api/forgejo/v1
+paths:
+  /version:
+    get:
+      summary: API version
+      description: Semantic version of the Forgejo API
+      operationId: getVersion
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/Version'
+components:
+  schemas:
+    Version:
+      type: object
+      properties:
+        version:
+          type: string
+
diff --git a/routers/api/forgejo/v1/api.go b/routers/api/forgejo/v1/api.go
new file mode 100644
index 000000000..33e9eb196
--- /dev/null
+++ b/routers/api/forgejo/v1/api.go
@@ -0,0 +1,16 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1
+
+import (
+	"code.gitea.io/gitea/modules/web"
+)
+
+func Routes() *web.Route {
+	m := web.NewRoute()
+	forgejo := NewForgejo()
+	m.Get("", Root)
+	m.Get("/version", forgejo.GetVersion)
+	return m
+}
diff --git a/routers/api/forgejo/v1/forgejo.go b/routers/api/forgejo/v1/forgejo.go
new file mode 100644
index 000000000..54ab19d7b
--- /dev/null
+++ b/routers/api/forgejo/v1/forgejo.go
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+
+package v1
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/json"
+)
+
+type Forgejo struct{}
+
+var _ ServerInterface = &Forgejo{}
+
+func NewForgejo() *Forgejo {
+	return &Forgejo{}
+}
+
+var ForgejoVersion = "development"
+
+func (f *Forgejo) GetVersion(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	_ = json.NewEncoder(w).Encode(Version{&ForgejoVersion})
+}
diff --git a/routers/api/forgejo/v1/generated.go b/routers/api/forgejo/v1/generated.go
new file mode 100644
index 000000000..725ddf572
--- /dev/null
+++ b/routers/api/forgejo/v1/generated.go
@@ -0,0 +1,167 @@
+// Package v1 provides primitives to interact with the openapi HTTP API.
+//
+// Code generated by github.com/deepmap/oapi-codegen version v1.12.4 DO NOT EDIT.
+package v1
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// Version defines model for Version.
+type Version struct {
+	Version *string `json:"version,omitempty"`
+}
+
+// ServerInterface represents all server handlers.
+type ServerInterface interface {
+	// API version
+	// (GET /version)
+	GetVersion(w http.ResponseWriter, r *http.Request)
+}
+
+// ServerInterfaceWrapper converts contexts to parameters.
+type ServerInterfaceWrapper struct {
+	Handler            ServerInterface
+	HandlerMiddlewares []MiddlewareFunc
+	ErrorHandlerFunc   func(w http.ResponseWriter, r *http.Request, err error)
+}
+
+type MiddlewareFunc func(http.Handler) http.Handler
+
+// GetVersion operation middleware
+func (siw *ServerInterfaceWrapper) GetVersion(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+
+	var handler http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		siw.Handler.GetVersion(w, r)
+	})
+
+	for _, middleware := range siw.HandlerMiddlewares {
+		handler = middleware(handler)
+	}
+
+	handler.ServeHTTP(w, r.WithContext(ctx))
+}
+
+type UnescapedCookieParamError struct {
+	ParamName string
+	Err       error
+}
+
+func (e *UnescapedCookieParamError) Error() string {
+	return fmt.Sprintf("error unescaping cookie parameter '%s'", e.ParamName)
+}
+
+func (e *UnescapedCookieParamError) Unwrap() error {
+	return e.Err
+}
+
+type UnmarshallingParamError struct {
+	ParamName string
+	Err       error
+}
+
+func (e *UnmarshallingParamError) Error() string {
+	return fmt.Sprintf("Error unmarshalling parameter %s as JSON: %s", e.ParamName, e.Err.Error())
+}
+
+func (e *UnmarshallingParamError) Unwrap() error {
+	return e.Err
+}
+
+type RequiredParamError struct {
+	ParamName string
+}
+
+func (e *RequiredParamError) Error() string {
+	return fmt.Sprintf("Query argument %s is required, but not found", e.ParamName)
+}
+
+type RequiredHeaderError struct {
+	ParamName string
+	Err       error
+}
+
+func (e *RequiredHeaderError) Error() string {
+	return fmt.Sprintf("Header parameter %s is required, but not found", e.ParamName)
+}
+
+func (e *RequiredHeaderError) Unwrap() error {
+	return e.Err
+}
+
+type InvalidParamFormatError struct {
+	ParamName string
+	Err       error
+}
+
+func (e *InvalidParamFormatError) Error() string {
+	return fmt.Sprintf("Invalid format for parameter %s: %s", e.ParamName, e.Err.Error())
+}
+
+func (e *InvalidParamFormatError) Unwrap() error {
+	return e.Err
+}
+
+type TooManyValuesForParamError struct {
+	ParamName string
+	Count     int
+}
+
+func (e *TooManyValuesForParamError) Error() string {
+	return fmt.Sprintf("Expected one value for %s, got %d", e.ParamName, e.Count)
+}
+
+// Handler creates http.Handler with routing matching OpenAPI spec.
+func Handler(si ServerInterface) http.Handler {
+	return HandlerWithOptions(si, ChiServerOptions{})
+}
+
+type ChiServerOptions struct {
+	BaseURL          string
+	BaseRouter       chi.Router
+	Middlewares      []MiddlewareFunc
+	ErrorHandlerFunc func(w http.ResponseWriter, r *http.Request, err error)
+}
+
+// HandlerFromMux creates http.Handler with routing matching OpenAPI spec based on the provided mux.
+func HandlerFromMux(si ServerInterface, r chi.Router) http.Handler {
+	return HandlerWithOptions(si, ChiServerOptions{
+		BaseRouter: r,
+	})
+}
+
+func HandlerFromMuxWithBaseURL(si ServerInterface, r chi.Router, baseURL string) http.Handler {
+	return HandlerWithOptions(si, ChiServerOptions{
+		BaseURL:    baseURL,
+		BaseRouter: r,
+	})
+}
+
+// HandlerWithOptions creates http.Handler with additional options
+func HandlerWithOptions(si ServerInterface, options ChiServerOptions) http.Handler {
+	r := options.BaseRouter
+
+	if r == nil {
+		r = chi.NewRouter()
+	}
+	if options.ErrorHandlerFunc == nil {
+		options.ErrorHandlerFunc = func(w http.ResponseWriter, r *http.Request, err error) {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+		}
+	}
+	wrapper := ServerInterfaceWrapper{
+		Handler:            si,
+		HandlerMiddlewares: options.Middlewares,
+		ErrorHandlerFunc:   options.ErrorHandlerFunc,
+	}
+
+	r.Group(func(r chi.Router) {
+		r.Get(options.BaseURL+"/version", wrapper.GetVersion)
+	})
+
+	return r
+}
diff --git a/routers/api/forgejo/v1/root.go b/routers/api/forgejo/v1/root.go
new file mode 100644
index 000000000..b976c5129
--- /dev/null
+++ b/routers/api/forgejo/v1/root.go
@@ -0,0 +1,14 @@
+// Copyright The Forgejo Authors.
+// SPDX-License-Identifier: MIT
+
+package v1
+
+import (
+	"net/http"
+)
+
+func Root(w http.ResponseWriter, r *http.Request) {
+	// https://www.rfc-editor.org/rfc/rfc8631
+	w.Header().Set("Link", "</assets/forgejo/api.v1.yml>; rel=\"service-desc\"")
+	w.WriteHeader(http.StatusNoContent)
+}
diff --git a/routers/init.go b/routers/init.go
index c1cfe26bc..66663d9d7 100644
--- a/routers/init.go
+++ b/routers/init.go
@@ -27,6 +27,7 @@ import (
 	"code.gitea.io/gitea/modules/translation"
 	"code.gitea.io/gitea/modules/web"
 	actions_router "code.gitea.io/gitea/routers/api/actions"
+	forgejo "code.gitea.io/gitea/routers/api/forgejo/v1"
 	packages_router "code.gitea.io/gitea/routers/api/packages"
 	apiv1 "code.gitea.io/gitea/routers/api/v1"
 	"code.gitea.io/gitea/routers/common"
@@ -175,6 +176,7 @@ func NormalRoutes() *web.Route {
 
 	r.Mount("/", web_routers.Routes())
 	r.Mount("/api/v1", apiv1.Routes())
+	r.Mount("/api/forgejo/v1", forgejo.Routes())
 	r.Mount("/api/internal", private.Routes())
 
 	r.Post("/-/fetch-redirect", common.FetchRedirectDelegate)
diff --git a/routers/web/misc/swagger-forgejo.go b/routers/web/misc/swagger-forgejo.go
new file mode 100644
index 000000000..2f539e955
--- /dev/null
+++ b/routers/web/misc/swagger-forgejo.go
@@ -0,0 +1,19 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package misc
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+)
+
+// tplSwagger swagger page template
+const tplForgejoSwagger base.TplName = "swagger/forgejo-ui"
+
+func SwaggerForgejo(ctx *context.Context) {
+	ctx.Data["APIVersion"] = "v1"
+	ctx.HTML(http.StatusOK, tplForgejoSwagger)
+}
diff --git a/routers/web/web.go b/routers/web/web.go
index f8b745fb1..13aaed994 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -262,6 +262,7 @@ func Routes() *web.Route {
 	if setting.API.EnableSwagger {
 		// Note: The route is here but no in API routes because it renders a web page
 		routes.Get("/api/swagger", append(mid, misc.Swagger)...) // Render V1 by default
+		routes.Get("/api/forgejo/swagger", append(mid, misc.SwaggerForgejo)...)
 	}
 
 	// TODO: These really seem like things that could be folded into Contexter or as helper functions
diff --git a/templates/swagger/forgejo-ui.tmpl b/templates/swagger/forgejo-ui.tmpl
new file mode 100644
index 000000000..d0ee88975
--- /dev/null
+++ b/templates/swagger/forgejo-ui.tmpl
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="UTF-8">
+		<title>Forgejo API</title>
+		<link href="{{AssetUrlPrefix}}/css/swagger.css?v={{AssetVersion}}" rel="stylesheet">
+	</head>
+	<body>
+		<a class="swagger-back-link" href="{{AppUrl}}">{{svg "octicon-reply"}}{{.locale.Tr "return_to_gitea"}}</a>
+		<div id="swagger-ui" data-source="{{AssetUrlPrefix}}/forgejo/api.{{.APIVersion}}.yml"></div>
+		<script src="{{AssetUrlPrefix}}/js/forgejoswagger.js?v={{AssetVersion}}"></script>
+	</body>
+</html>
diff --git a/tests/integration/api_forgejo_root_test.go b/tests/integration/api_forgejo_root_test.go
new file mode 100644
index 000000000..d21c9449b
--- /dev/null
+++ b/tests/integration/api_forgejo_root_test.go
@@ -0,0 +1,21 @@
+// Copyright The Forgejo Authors.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"net/http"
+	"testing"
+
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAPIForgejoRoot(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	req := NewRequest(t, "GET", "/api/forgejo/v1")
+	resp := MakeRequest(t, req, http.StatusNoContent)
+	assert.Contains(t, resp.Header().Get("Link"), "/assets/forgejo/api.v1.yml")
+}
diff --git a/tests/integration/api_forgejo_version_test.go b/tests/integration/api_forgejo_version_test.go
new file mode 100644
index 000000000..b8b8de8ee
--- /dev/null
+++ b/tests/integration/api_forgejo_version_test.go
@@ -0,0 +1,25 @@
+// Copyright The Forgejo Authors.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"net/http"
+	"testing"
+
+	"code.gitea.io/gitea/routers/api/forgejo/v1"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAPIForgejoVersion(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+
+	req := NewRequest(t, "GET", "/api/forgejo/v1/version")
+	resp := MakeRequest(t, req, http.StatusOK)
+
+	var version v1.Version
+	DecodeJSON(t, resp, &version)
+	assert.Equal(t, "development", *version.Version)
+}
diff --git a/web_src/js/standalone/forgejo-swagger.js b/web_src/js/standalone/forgejo-swagger.js
new file mode 100644
index 000000000..b565827b3
--- /dev/null
+++ b/web_src/js/standalone/forgejo-swagger.js
@@ -0,0 +1,22 @@
+import SwaggerUI from 'swagger-ui-dist/swagger-ui-es-bundle.js';
+import 'swagger-ui-dist/swagger-ui.css';
+
+window.addEventListener('load', async () => {
+  const url = document.getElementById('swagger-ui').getAttribute('data-source');
+
+  const ui = SwaggerUI({
+    url: url,
+    dom_id: '#swagger-ui',
+    deepLinking: true,
+    docExpansion: 'none',
+    defaultModelRendering: 'model', // don't show examples by default, because they may be incomplete
+    presets: [
+      SwaggerUI.presets.apis
+    ],
+    plugins: [
+      SwaggerUI.plugins.DownloadUrl
+    ]
+  });
+
+  window.ui = ui;
+});
diff --git a/webpack.config.js b/webpack.config.js
index 448dc6400..b5923164c 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -76,6 +76,10 @@ export default {
     webcomponents: [
       fileURLToPath(new URL('web_src/js/webcomponents/webcomponents.js', import.meta.url)),
     ],
+    forgejoswagger: [ // Forgejo swagger is OpenAPI 3.0.0 and has specific parameters
+      fileURLToPath(new URL('web_src/js/standalone/forgejo-swagger.js', import.meta.url)),
+      fileURLToPath(new URL('web_src/css/standalone/swagger.css', import.meta.url)),
+    ],
     swagger: [
       fileURLToPath(new URL('web_src/js/standalone/swagger.js', import.meta.url)),
       fileURLToPath(new URL('web_src/css/standalone/swagger.css', import.meta.url)),