diff --git a/Gemfile b/Gemfile
index 6928572547c..49d2bf09bdb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -10,7 +10,7 @@ gem "clearance", "~> 2.6"
 gem "dalli", "~> 3.2"
 gem "ddtrace", "~> 1.10", require: "ddtrace/auto_instrument"
 gem "dogstatsd-ruby", "~> 5.5"
-gem "google-protobuf", "~> 3.22"
+gem "google-protobuf", "~> 3.23"
 gem "faraday", "~> 1.10"
 gem "good_job", "~> 3.14"
 gem "gravtastic", "~> 3.2"
@@ -73,6 +73,7 @@ group :development, :test do
   gem "toxiproxy", "~> 2.0"
   gem "factory_bot_rails", "~> 6.2"
   gem "dotenv-rails", "~> 2.8"
+  gem "openapi_parser", "~> 1.0"
 
   gem "brakeman", "~> 5.4", require: false
   gem "rubocop", "~> 1.48", require: false
@@ -87,6 +88,7 @@ group :development do
   gem "listen", "~> 3.8"
   gem "letter_opener", "~> 1.8"
   gem "letter_opener_web", "~> 2.0"
+  gem "rswag-ui", "~> 2.9"
 end
 
 group :test do
diff --git a/Gemfile.lock b/Gemfile.lock
index d1b0c020af9..3a149832bd4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -360,6 +360,7 @@ GEM
     omniauth-rails_csrf_protection (1.0.1)
       actionpack (>= 4.2)
       omniauth (~> 2.0)
+    openapi_parser (1.0.0)
     opensearch-api (1.0.0)
       multi_json
     opensearch-dsl (0.2.1)
@@ -466,6 +467,9 @@ GEM
       chunky_png (~> 1.0)
       rqrcode_core (~> 1.0)
     rqrcode_core (1.2.0)
+    rswag-ui (2.9.0)
+      actionpack (>= 3.1, < 7.1)
+      railties (>= 3.1, < 7.1)
     rubocop (1.48.0)
       json (~> 2.3)
       parallel (~> 1.10)
@@ -632,7 +636,7 @@ DEPENDENCIES
   faraday (~> 1.10)
   faraday_middleware-aws-sigv4 (~> 0.6)
   good_job (~> 3.14)
-  google-protobuf (~> 3.22)
+  google-protobuf (~> 3.23)
   gravtastic (~> 3.2)
   groupdate (~> 6.2)
   high_voltage (~> 3.1)
@@ -653,6 +657,7 @@ DEPENDENCIES
   omniauth (~> 2.1)
   omniauth-github (~> 2.0)
   omniauth-rails_csrf_protection (~> 1.0)
+  openapi_parser (~> 1.0)
   opensearch-dsl (~> 0.2.0)
   opensearch-ruby (~> 1.0)
   pg (~> 1.4)
@@ -672,6 +677,7 @@ DEPENDENCIES
   roadie-rails (~> 3.0)
   rotp (~> 6.2)
   rqrcode (~> 2.1)
+  rswag-ui (~> 2.9)
   rubocop (~> 1.48)
   rubocop-capybara (~> 2.17)
   rubocop-minitest (~> 0.29)
diff --git a/app/controllers/api/base_controller.rb b/app/controllers/api/base_controller.rb
index db60595fd7f..0eb48bdd944 100644
--- a/app/controllers/api/base_controller.rb
+++ b/app/controllers/api/base_controller.rb
@@ -1,6 +1,8 @@
 class Api::BaseController < ApplicationController
   skip_before_action :verify_authenticity_token
 
+  around_action :rswag
+
   private
 
   def name_params
@@ -117,4 +119,38 @@ def render_api_key_forbidden
   def render_soft_deleted_api_key
     render plain: "An invalid API key cannot be used. Please delete it and create a new one.", status: :forbidden
   end
+
+  def rswag
+    f = Rails.root.join("app", "controllers", "api", "v1", "api.yaml")
+    schema = OpenAPIParser.load(f, { strict_reference_validation: true, strict_response_validation: true })
+    path = request.path
+    path = path.delete_suffix(".#{request.format.to_sym}")
+    path = path.sub("/api/v1", "")
+
+    ro = schema.request_operation(request.method.downcase.to_sym, path)
+    raise "No operation found for #{request.method} #{path}" unless ro
+
+    ro.validate_request_body(request.content_mime_type.to_s, request.request_parameters)
+    ro.validate_path_params
+
+    yield.tap do
+      ro.validate_response_body(
+        OpenAPIParser::RequestOperation::ValidatableResponseBody.new(response.status, deserialized_response_body, response.headers)
+      )
+    end
+  end
+
+  def deserialized_response_body
+    case Mime::Type.lookup response.content_type.sub(/^([^,;]*).*/, '\1').strip.downcase
+    when Mime::Type.lookup_by_extension(:json)
+      JSON.parse(response.body)
+    when Mime::Type.lookup_by_extension(:yaml)
+      YAML.safe_load(response.body)
+    when Mime::Type.lookup("text/plain")
+      response.body
+    else
+      raise "Unknown content type #{response.content_type} (#{response.content_type.sub(/^([^,;]*).*/, '\1')}) in response body: " +
+        response.body
+    end
+  end
 end
diff --git a/app/controllers/api/v1/api.yaml b/app/controllers/api/v1/api.yaml
new file mode 100644
index 00000000000..5749a816387
--- /dev/null
+++ b/app/controllers/api/v1/api.yaml
@@ -0,0 +1,686 @@
+openapi: 3.0.0
+x-stoplight:
+  id: ke9efxx0sv0in
+info:
+  title: RubyGems.org API
+  version: 1.0.0
+  contact:
+    email: support@rubygems.org
+servers:
+  - url: "https://rubygems.org/api/v1"
+    description: Production
+  - url: "https://staging.rubygems.org/api/v1"
+    description: Staging
+tags:
+  - name: dependencies
+  - name: gems
+  - name: web_hooks
+paths:
+  /gems:
+    get:
+      responses:
+        "200":
+          description: OK
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: "#/components/schemas/Rubygem"
+            text/yaml:
+              schema:
+                type: array
+                items:
+                  $ref: "#/components/schemas/Rubygem"
+        "401":
+          $ref: "#/components/responses/Unauthorized"
+        "403":
+          $ref: "#/components/responses/Forbidden"
+      tags:
+        - gems
+    post:
+      operationId: pushGem
+      requestBody:
+        content:
+          application/x-www-form-urlencoded:
+            schema:
+              type: object
+        description: The .gem file to push
+      responses:
+        "200":
+          description: Created
+          content:
+            text/plain:
+              schema:
+                type: string
+                example: "Successfully registered gem: rubygem1 (1.1.0.pre.2)"
+        4XX:
+          $ref: "#/components/responses/Error"
+  "/gems/{name}":
+    parameters:
+      - name: name
+        in: path
+        required: true
+        schema:
+          $ref: "#/components/schemas/GemName"
+    get:
+      responses:
+        "200":
+          description: OK
+          content:
+            text/yaml:
+              schema:
+                $ref: "#/components/schemas/Rubygem"
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Rubygem"
+              example:
+                name: rubygem1
+                downloads: 0
+                version: 1.1.0.pre.2
+                version_created_at: "2023-06-24T01:22:24.352Z"
+                version_downloads: 0
+                platform: ruby
+                authors: null
+                info: This rubygem does not have a description or summary.
+                licenses: null
+                metadata: {}
+                yanked: false
+                sha: null
+                project_uri: "http://localhost/gems/rubygem1"
+                gem_uri: "http://localhost/gems/rubygem1-1.1.0.pre.2.gem"
+                homepage_uri: null
+                wiki_uri: null
+                documentation_uri: "https://www.rubydoc.info/gems/rubygem1/1.1.0.pre.2"
+                mailing_list_uri: null
+                source_code_uri: null
+                bug_tracker_uri: null
+                changelog_uri: null
+                funding_uri: null
+                dependencies:
+                  development: []
+                  runtime:
+                    - name: rubygem0
+                      requirements: ~> 1.0.0
+        "403":
+          $ref: "#/components/responses/Forbidden"
+        "404":
+          $ref: "#/components/responses/Error"
+      tags:
+        - gems
+    options:
+      responses:
+        "200":
+          description: OK
+          content:
+            text/plain:
+              schema:
+                type: string
+  "/gems/{name}/reverse_dependencies":
+    get:
+      parameters:
+        - name: name
+          in: path
+          required: true
+          schema:
+            $ref: "#/components/schemas/GemName"
+      responses:
+        "200":
+          description: OK
+          content:
+            text/yaml:
+              schema:
+                $ref: "#/components/schemas/ReverseDependencies"
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ReverseDependencies"
+        "403":
+          $ref: "#/components/responses/Forbidden"
+        "404":
+          $ref: "#/components/responses/Error"
+      tags:
+        - gems
+        - dependencies
+  /web_hooks:
+    post:
+      operationId: createWebHook
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+              additionalProperties: false
+        description: The webhook to create
+      responses:
+        "201":
+          description: Created
+          content:
+            text/plain:
+              schema:
+                type: string
+        4XX:
+          $ref: "#/components/responses/Error"
+      tags:
+        - web_hooks
+    get:
+      responses:
+        "200":
+          description: OK
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  all gems:
+                    type: array
+                    items:
+                      $ref: "#/components/schemas/WebHook"
+                additionalProperties:
+                  type: array
+                  items:
+                    $ref: "#/components/schemas/WebHook"
+            text/yaml:
+              schema:
+                type: object
+                properties:
+                  all gems:
+                    type: array
+                    items:
+                      $ref: "#/components/schemas/WebHook"
+                additionalProperties:
+                  type: array
+                  items:
+                    $ref: "#/components/schemas/WebHook"
+        4XX:
+          $ref: "#/components/responses/Error"
+      tags:
+        - web_hooks
+    delete:
+      operationId: deleteWebHook
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+        description: The webhook to delete
+      responses:
+        "200":
+          description: OK
+          content:
+            text/plain:
+              schema:
+                type: string
+        4XX:
+          $ref: "#/components/responses/Error"
+      tags:
+        - web_hooks
+  /web_hooks/fire:
+    post:
+      operationId: fireWebHook
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+              additionalProperties: false
+              required:
+                - url
+              properties:
+                gem_name:
+                  $ref: "#/components/schemas/GemName"
+                  nullable: true
+                url:
+                  type: string
+                  format: uri
+          text/yaml:
+            schema:
+              type: object
+              additionalProperties: false
+              properties:
+                gem_name:
+                  oneOf:
+                    - $ref: "#/components/schemas/GemName"
+                    - type: string
+                      enum:
+                        - "*"
+                  nullable: true
+                url:
+                  type: string
+                  format: uri
+          "*/*":
+            schema:
+              type: object
+              additionalProperties: false
+              properties:
+                gem_name:
+                  oneOf:
+                    - $ref: "#/components/schemas/GemName"
+                    - type: string
+                      enum:
+                        - "*"
+                  nullable: true
+                url:
+                  type: string
+                  format: uri
+        description: The webhook to fire
+      responses:
+        "200":
+          description: Fired
+          content:
+            text/plain:
+              schema:
+                type: string
+        4XX:
+          $ref: "#/components/responses/Error"
+      tags:
+        - web_hooks
+  /web_hooks/remove:
+    delete:
+      responses:
+        "200":
+          description: Deleted
+          content:
+            text/plain:
+              schema:
+                type: string
+        4XX:
+          $ref: "#/components/responses/Error"
+      tags:
+        - web_hooks
+  "/versions/{gem_name}":
+    parameters:
+      - schema:
+          $ref: "#/components/schemas/GemName"
+        name: gem_name
+        in: path
+        required: true
+    get:
+      tags:
+        - versions
+      responses:
+        "200":
+          description: OK
+          content:
+            text/yaml:
+              schema:
+                type: array
+                items:
+                  $ref: "#/components/schemas/Version"
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: "#/components/schemas/Version"
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "304":
+          $ref: "#/components/responses/NotModified"
+      operationId: getGemVersions
+  /versions/{gem_name}/latest:
+    parameters:
+      - schema:
+          $ref: "#/components/schemas/GemName"
+        name: gem_name
+        in: path
+        required: true
+    get:
+      tags:
+        - versions
+      responses:
+        "200":
+          description: OK
+          content:
+            text/yaml:
+              schema:
+                type: object
+                properties:
+                  version:
+                    oneOf:
+                      - $ref: "#/components/schemas/VersionString"
+                      - type: string
+                        enum:
+                          - "unknown"
+                additionalProperties: false
+            application/json:
+              schema:
+                type: object
+                properties:
+                  version:
+                    oneOf:
+                      - type: string
+                        enum:
+                          - "unknown"
+                      - $ref: "#/components/schemas/VersionString"
+                additionalProperties: false
+            text/javascript:
+              schema:
+                type: string
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "304":
+          $ref: "#/components/responses/NotModified"
+      operationId: getLatestGemVersion
+  /versions/{gem_name}/reverse_dependencies:
+    parameters:
+      - schema:
+          $ref: "#/components/schemas/GemName"
+        name: gem_name
+        in: path
+        required: true
+    get:
+      tags:
+        - versions
+      responses:
+        "200":
+          description: OK
+          content:
+            text/yaml:
+              schema:
+                type: array
+                items:
+                  type: string
+            application/json:
+              schema:
+                type: array
+                items:
+                  type: string
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "304":
+          $ref: "#/components/responses/NotModified"
+      operationId: getReverseDependencies
+  /api_key:
+    get:
+      tags:
+        - api_key
+      responses:
+        "200":
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ApiKey"
+            application/x-yaml:
+              schema:
+                $ref: "#/components/schemas/ApiKey"
+            text/plain:
+              schema:
+                type: string
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "401":
+          $ref: "#/components/responses/Unauthorized"
+      operationId: getApiKey
+    post:
+      tags:
+        - api_key
+      responses:
+        "200":
+          description: OK
+          content:
+            text/plain:
+              schema:
+                type: string
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "401":
+          $ref: "#/components/responses/Unauthorized"
+      operationId: signIn
+    put:
+      tags:
+        - api_key
+      responses:
+        "200":
+          description: OK
+          content:
+            text/plain:
+              schema:
+                type: string
+        "4XX":
+          $ref: "#/components/responses/Error"
+        "401":
+          $ref: "#/components/responses/Unauthorized"
+      operationId: updateApiKey
+components:
+  schemas:
+    GemName:
+      type: string
+      pattern: '\A[A-Za-z0-9\.\-_]+\z'
+    VersionString:
+      type: string
+      pattern: '\A([0-9]+(?>\.[0-9a-zA-Z]+)*(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?)?\z'
+      x-stoplight:
+        id: 1037iwcuunjvw
+    Rubygem:
+      type: object
+      x-stoplight:
+        id: kfk9i6uptmzzr
+      additionalProperties: false
+      properties:
+        name:
+          $ref: "#/components/schemas/GemName"
+        downloads:
+          type: integer
+        version:
+          $ref: "#/components/schemas/VersionString"
+        version_created_at:
+          type: string
+          format: date-time
+        version_downloads:
+          type: integer
+        platform:
+          type: string
+        authors:
+          type: string
+          nullable: true
+        info:
+          type: string
+        licenses:
+          type: string
+          nullable: true
+        metadata:
+          type: object
+          nullable: true
+        yanked:
+          type: boolean
+        sha:
+          type: string
+          nullable: true
+        project_uri:
+          type: string
+          format: uri
+        gem_uri:
+          type: string
+          format: uri
+        homepage_uri:
+          type: string
+          format: uri
+          nullable: true
+        wiki_uri:
+          type: string
+          format: uri
+          nullable: true
+        documentation_uri:
+          type: string
+          format: uri
+          nullable: true
+        mailing_list_uri:
+          type: string
+          format: uri
+          nullable: true
+        source_code_uri:
+          type: string
+          format: uri
+          nullable: true
+        bug_tracker_uri:
+          type: string
+          format: uri
+          nullable: true
+        changelog_uri:
+          type: string
+          format: uri
+          nullable: true
+        funding_uri:
+          type: string
+          format: uri
+          nullable: true
+        dependencies:
+          type: object
+          additionalProperties: false
+          properties:
+            development:
+              type: array
+              items:
+                $ref: "#/components/schemas/Dependency"
+            runtime:
+              type: array
+              items:
+                $ref: "#/components/schemas/Dependency"
+    ReverseDependencies:
+      type: array
+      items:
+        type: string
+      x-stoplight:
+        id: drr3o1k6z2j54
+    Dependency:
+      type: object
+      additionalProperties: false
+      properties:
+        name:
+          $ref: "#/components/schemas/GemName"
+        requirements:
+          type: string
+          nullable: true
+    WebHook:
+      type: object
+      additionalProperties: false
+      required:
+        - url
+        - failure_count
+      properties:
+        url:
+          type: string
+          format: uri
+        failure_count:
+          type: integer
+    Version:
+      type: object
+      additionalProperties: false
+      properties:
+        authors:
+          type: string
+          nullable: true
+        built_at:
+          type: string
+          format: date-time
+        created_at:
+          type: string
+          format: date-time
+        description:
+          type: string
+          nullable: true
+        downloads_count:
+          type: integer
+        metadata:
+          type: object
+          nullable: true
+          additionalProperties:
+            type: string
+            maxLength: 1024
+        number:
+          $ref: "#/components/schemas/VersionString"
+        summary:
+          type: string
+          nullable: true
+        platform:
+          type: string
+          nullable: true
+        rubygems_version:
+          type: string
+          nullable: true
+        ruby_version:
+          type: string
+          nullable: true
+        prerelease:
+          type: boolean
+        licenses:
+          type: string
+          nullable: true
+        requirements:
+          type: string
+          # additionalProperties: false
+          # properties:
+          #   development:
+          #     type: array
+          #     items:
+          #       $ref: "#/components/schemas/Dependency"
+          #   runtime:
+          #     type: array
+          #     items:
+          #       $ref: "#/components/schemas/Dependency"
+        sha:
+          type: string
+          nullable: true
+    ApiKey:
+      type: object
+      additionalProperties: false
+      required:
+        - rubygems_api_key
+        - status
+      properties:
+        rubygems_api_key:
+          type: string
+        status:
+          type: string
+  responses:
+    Forbidden:
+      description: Forbidden
+      content:
+        text/plain:
+          schema:
+            type: string
+            example: Forbidden
+    Unauthorized:
+      description: Forbidden
+      content:
+        text/plain:
+          schema:
+            type: string
+            example: "Access Denied. Please sign up for an account at https://rubygems.org"
+        application/json:
+          schema:
+            type: string
+        "":
+          schema:
+            type: string
+    NotModified:
+      description: Not Modified
+      content:
+        "":
+          schema:
+            type: string
+            example: Not Modified
+    Error:
+      description: Error
+      content:
+        application/json:
+          schema:
+            type: object
+            additionalProperties: false
+            properties:
+              status:
+                type: integer
+                example: 404
+              error:
+                type: string
+                example: Not Found
+        text/plain:
+          schema:
+            type: string
+            example: This gem could not be found
+  securitySchemes:
+    API Key:
+      name: Authorization
+      type: apiKey
+      in: header
+      description: ""
diff --git a/app/controllers/api/v1/schema_controller.rb b/app/controllers/api/v1/schema_controller.rb
new file mode 100644
index 00000000000..a73d02cb886
--- /dev/null
+++ b/app/controllers/api/v1/schema_controller.rb
@@ -0,0 +1,9 @@
+class Api::V1::SchemaController < Api::BaseController
+  def show
+    schema = YAML.load Rails.root.join("app", "controllers", "api", "v1", "api.yaml").read
+    respond_to do |format|
+      format.json { render json: schema }
+      format.yaml { render yaml: schema }
+    end
+  end
+end
diff --git a/config/initializers/rswag_ui.rb b/config/initializers/rswag_ui.rb
new file mode 100644
index 00000000000..057c17a6693
--- /dev/null
+++ b/config/initializers/rswag_ui.rb
@@ -0,0 +1,17 @@
+if Rails.env.development?
+  Rswag::Ui.configure do |c|
+    # List the Swagger endpoints that you want to be documented through the
+    # swagger-ui. The first parameter is the path (absolute or relative to the UI
+    # host) to the corresponding endpoint and the second is a title that will be
+    # displayed in the document selector.
+    # NOTE: If you're using rspec-api to expose Swagger files
+    # (under swagger_root) as JSON or YAML endpoints, then the list below should
+    # correspond to the relative paths for those endpoints.
+
+    c.swagger_endpoint '/api/v1/schema.yaml', 'API V1 Docs'
+
+    # Add Basic Auth in case your API is private
+    # c.basic_auth_enabled = true
+    # c.basic_auth_credentials 'username', 'password'
+  end
+end
diff --git a/config/routes.rb b/config/routes.rb
index 2be100f3548..d95b0eafe1e 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -284,5 +284,9 @@
   ################################################################################
   # Development routes
 
-  mount LetterOpenerWeb::Engine, at: "/letter_opener" if Rails.env.development?
+  if Rails.env.development?
+    mount LetterOpenerWeb::Engine, at: "/letter_opener"
+    get '/api/v1/schema' => 'api/v1/schema#show'
+    mount Rswag::Ui::Engine => '/api-docs'
+  end
 end