diff --git a/config/initializers/gitlab_grape_openapi.rb b/config/initializers/gitlab_grape_openapi.rb
index be24b8aa85cb4bfbf4cec53059f412c099f36c9b..1d14c4be5479c523e161f8a30ef3a0011e23355c 100644
--- a/config/initializers/gitlab_grape_openapi.rb
+++ b/config/initializers/gitlab_grape_openapi.rb
@@ -11,6 +11,10 @@
     terms_of_service: 'https://about.gitlab.com/terms/'
   )
 
+  config.api_prefix = "api"
+
+  config.api_version = "v4"
+
   config.servers = [
     Gitlab::GrapeOpenapi::Models::Server.new(
       url: Gitlab::Utils.append_path(Gitlab.config.gitlab.url, "api/v4"),
diff --git a/gems/gitlab-grape-openapi/README.md b/gems/gitlab-grape-openapi/README.md
index 489e628ab56ee5d70e49e4ddc43959d5aea345d4..b87abf6184be64e977b4eb6baf1fe1596caadf2b 100644
--- a/gems/gitlab-grape-openapi/README.md
+++ b/gems/gitlab-grape-openapi/README.md
@@ -3,7 +3,7 @@
 > [!warning]
 > This gem is currently designed entirely for internal use at GitLab. This gem is not functional and not used in production.
 
-Internal gem for generating OpenAPI 3.1 specifications from Grape API definitions.
+Internal gem for generating OpenAPI 3.0 specifications from Grape API definitions.
 
 ## Usage
 
diff --git a/gems/gitlab-grape-openapi/gitlab-grape-openapi.gemspec b/gems/gitlab-grape-openapi/gitlab-grape-openapi.gemspec
index 41c5db8b7e3030da25e60624f4c5f7e993fdfe8a..e360fa2b0c8e1071a644d7d5d6ae421ce0268330 100644
--- a/gems/gitlab-grape-openapi/gitlab-grape-openapi.gemspec
+++ b/gems/gitlab-grape-openapi/gitlab-grape-openapi.gemspec
@@ -8,8 +8,8 @@ Gem::Specification.new do |spec|
   spec.authors = ["group::api"]
   spec.email = ["engineering@gitlab.com"]
 
-  spec.summary       = "Generate OpenAPI 3.1 specifications from Grape APIs"
-  spec.description   = "A Ruby gem that introspects Grape API definitions and generates OpenAPI 3.1 specification files"
+  spec.summary       = "Generate OpenAPI 3.0 specifications from Grape APIs"
+  spec.description   = "A Ruby gem that introspects Grape API definitions and generates OpenAPI 3.0 specification files"
   spec.license = "MIT"
   spec.required_ruby_version = ">= 3.2.0"
 
diff --git a/gems/gitlab-grape-openapi/lib/gitlab-grape-openapi.rb b/gems/gitlab-grape-openapi/lib/gitlab-grape-openapi.rb
index 4a190df3e7cfe387551b86487da68a1b63511549..0f2fad56b8d49b7f0748e00bfffd310c76447f2b 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab-grape-openapi.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab-grape-openapi.rb
@@ -10,11 +10,15 @@
 require_relative "gitlab/grape_openapi/converters/entity_converter"
 require_relative "gitlab/grape_openapi/converters/type_resolver"
 require_relative "gitlab/grape_openapi/converters/tag_converter"
+require_relative "gitlab/grape_openapi/converters/operation_converter"
+require_relative "gitlab/grape_openapi/converters/path_converter"
 
 # Models
 require_relative "gitlab/grape_openapi/models/schema"
 require_relative "gitlab/grape_openapi/models/tag"
 require_relative "gitlab/grape_openapi/models/server"
+require_relative "gitlab/grape_openapi/models/operation"
+require_relative "gitlab/grape_openapi/models/path_item"
 require_relative "gitlab/grape_openapi/models/security_scheme"
 require_relative "gitlab/grape_openapi/models/info"
 
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/configuration.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/configuration.rb
index 3a84611cc8640067f20d5bb4ee49dbbb7b90667b..d3d9cf8bcb5c853ed7376669fc333d26d2e98dd1 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/configuration.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/configuration.rb
@@ -3,11 +3,13 @@
 module Gitlab
   module GrapeOpenapi
     class Configuration
-      attr_accessor :api_version, :servers, :security_schemes, :info
+      attr_accessor :api_version, :api_prefix, :servers, :security_schemes, :info
 
       def initialize
-        @api_version = "v4"
+        @api_prefix = "api"
+        @api_version = "v1"
         @info = nil
+
         @servers = []
         @security_schemes = []
       end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/operation_converter.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/operation_converter.rb
new file mode 100644
index 0000000000000000000000000000000000000000..7f38eceff5cefd4e8bf39eeaf5df23ba01581e31
--- /dev/null
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/operation_converter.rb
@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GrapeOpenapi
+    module Converters
+      class OperationConverter
+        # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#operation-object
+        def self.convert(route)
+          new(route).convert
+        end
+
+        def initialize(route)
+          @route = route
+          @config = Gitlab::GrapeOpenapi.configuration
+        end
+
+        def convert
+          Models::Operation.new.tap do |operation|
+            operation.operation_id = operation_id
+            operation.description = extract_description
+            operation.tags = extract_tags
+          end
+        end
+
+        private
+
+        attr_reader :config, :route
+
+        def operation_id
+          method = http_method.downcase
+          normalized = normalized_path
+          segments = normalized.split('/').reject(&:empty?)
+
+          parts = segments.filter_map do |seg|
+            next 'Dash' if seg == '-'
+
+            if seg.start_with?('{')
+              param_name = seg[1..-2]
+              camelize(param_name)
+            else
+              camelize(seg)
+            end
+          end
+
+          "#{method}#{parts.join}"
+        end
+
+        def extract_description
+          description_from_options = options[:description]
+          return description_from_options[:description] if description_from_options.is_a?(Hash)
+          return description_from_options if description_from_options.is_a?(String)
+
+          return unless endpoint
+
+          description_hash = endpoint.instance_variable_get(:@inheritable_setting)&.namespace
+          description_hash[:description] if description_hash.is_a?(Hash)
+        end
+
+        def extract_tags
+          segments = path_segments
+          return [] if segments.empty?
+
+          [segments.first]
+        end
+
+        def path_segments
+          segments = normalized_path.split('/').reject do |segment|
+            segment.empty? || segment.start_with?('{')
+          end
+
+          segments.reject { |seg| seg == config.api_prefix || seg == config.api_version || seg == '-' }
+        end
+
+        def normalized_path
+          path = pattern.instance_variable_get(:@origin)
+          path
+            .gsub(/\(\.:format\)$/, '')
+            .gsub(/:\w+/) { |match| "{#{match[1..]}}" }
+            .gsub('{version}', config.api_version)
+        end
+
+        def camelize(string)
+          string.gsub(/[@.-]/, '_').split('_').reject(&:empty?).map(&:capitalize).join
+        end
+
+        def http_method
+          options[:method]
+        end
+
+        def pattern
+          route.instance_variable_get(:@pattern)
+        end
+
+        def options
+          route.instance_variable_get(:@options)
+        end
+
+        def endpoint
+          route.instance_variable_get(:@app)
+        end
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/path_converter.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/path_converter.rb
new file mode 100644
index 0000000000000000000000000000000000000000..073c463bb2481800b353b6c31277498dc1f55fce
--- /dev/null
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/converters/path_converter.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GrapeOpenapi
+    module Converters
+      class PathConverter
+        # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#paths-object
+        def self.convert(routes)
+          new(routes).convert
+        end
+
+        def initialize(routes)
+          @routes = routes
+          @config = Gitlab::GrapeOpenapi.configuration
+        end
+
+        def convert
+          grouped_routes.transform_values do |routes_for_path|
+            build_path_item(routes_for_path)
+          end
+        end
+
+        private
+
+        attr_reader :config, :routes
+
+        def grouped_routes
+          routes.group_by { |route| normalize_path(route) }
+        end
+
+        def normalize_path(route)
+          pattern = route.instance_variable_get(:@pattern)
+          path = pattern.instance_variable_get(:@origin)
+
+          path
+            .gsub(/\(\.:format\)$/, '')
+            .gsub(/:\w+/) { |match| "{#{match[1..]}}" }
+            .gsub('{version}', config.api_version)
+        end
+
+        def build_path_item(routes_for_path)
+          path_item = Models::PathItem.new
+
+          routes_for_path.each do |route|
+            operation = OperationConverter.convert(route)
+            method = extract_method(route)
+            path_item.add_operation(method, operation)
+          end
+
+          path_item.to_h
+        end
+
+        def extract_method(route)
+          options = route.instance_variable_get(:@options)
+          options[:method]
+        end
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/generator.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/generator.rb
index 9041bd09baf890222a8bdf7e8709338d19fc4bd9..91819c18163c2a62ea36769b3e52feee8b6af0d0 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/generator.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/generator.rb
@@ -21,7 +21,8 @@ def generate
           info: Gitlab::GrapeOpenapi.configuration.info.to_h,
           tags: tag_registry.tags,
           servers: Gitlab::GrapeOpenapi.configuration.servers.map(&:to_h),
-          paths: {}, # TODO: https://gitlab.com/gitlab-org/gitlab/-/issues/572540
+
+          paths: paths,
           components: {
             securitySchemes: security_schemes
           },
@@ -40,6 +41,11 @@ def initialize_tags
           Converters::TagConverter.new(api_class, tag_registry).convert
         end
       end
+
+      def paths
+        all_routes = @api_classes.flat_map(&:routes)
+        Converters::PathConverter.convert(all_routes)
+      end
     end
   end
 end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/operation.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/operation.rb
new file mode 100644
index 0000000000000000000000000000000000000000..52dbd06b7afeeaf64afe002393469f452b9f7ad7
--- /dev/null
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/operation.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GrapeOpenapi
+    module Models
+      class Operation
+        # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#operation-object
+        attr_accessor :operation_id, :description, :tags, :responses
+
+        def initialize
+          @tags = []
+        end
+
+        def to_h
+          {
+            operationId: operation_id,
+            description: description,
+            tags: tags.empty? ? nil : tags,
+            responses: responses
+          }.compact
+        end
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/path_item.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/path_item.rb
new file mode 100644
index 0000000000000000000000000000000000000000..b882da37c2a6dc6ae01f82111cbec337fbafe850
--- /dev/null
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/path_item.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GrapeOpenapi
+    module Models
+      class PathItem
+        # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#path-item-object
+        attr_reader :operations
+
+        def initialize
+          @operations = {}
+        end
+
+        def add_operation(method, operation)
+          @operations[method.to_s.downcase] = operation
+        end
+
+        def to_h
+          operations.transform_values(&:to_h)
+        end
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/schema.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/schema.rb
index 3945e005c94ca9c89d4c72ed25f87be06dd42b68..e5f80682608e2adbbdf7a692bccf2f944ccaced9 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/schema.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/schema.rb
@@ -3,7 +3,7 @@
 module Gitlab
   module GrapeOpenapi
     module Models
-      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#schema-object
+      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#schema-object
       class Schema
         attr_accessor :properties, :type
 
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/security_scheme.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/security_scheme.rb
index b67440313e756649667c6209d27002d531c80b22..43fab90a08491c37d14ac73f93068d1ab325cf3a 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/security_scheme.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/security_scheme.rb
@@ -3,7 +3,7 @@
 module Gitlab
   module GrapeOpenapi
     module Models
-      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#security-scheme-object
+      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#security-scheme-object
       class SecurityScheme
         VALID_TYPES = %w[apiKey http oauth2 openIdConnect].freeze
         VALID_IN_VALUES = %w[query header cookie].freeze
diff --git a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/server.rb b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/server.rb
index 88b5d57448b7b1a624e1b40a3a890cb315535e04..4632a4b2e1b93f44a29b18aea50137ab7fcbc0a2 100644
--- a/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/server.rb
+++ b/gems/gitlab-grape-openapi/lib/gitlab/grape_openapi/models/server.rb
@@ -3,7 +3,7 @@
 module Gitlab
   module GrapeOpenapi
     module Models
-      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#server-object
+      # https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.0.md#server-object
       class Server
         attr_reader :url, :description
 
diff --git a/gems/gitlab-grape-openapi/spec/fixtures/apis/nested_api.rb b/gems/gitlab-grape-openapi/spec/fixtures/apis/nested_api.rb
new file mode 100644
index 0000000000000000000000000000000000000000..db762d7eba09042a5326d3f53053ab95f41619ac
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/fixtures/apis/nested_api.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+# rubocop:disable API/Base -- Test fixture
+module TestApis
+  class NestedApi < Grape::API
+    desc 'No nesting'
+    get '/api/:version/users' do
+      status 200
+      [
+        { id: 1, name: 'John Doe', email: 'john@example.com' },
+        { id: 2, name: 'Jane Smith', email: 'jane@example.com' }
+      ]
+    end
+
+    desc '1 level of nesting'
+    get '/api/:version/admin/users' do
+      status 200
+      [
+        { id: 1, name: 'Admin User', email: 'admin@example.com', role: 'admin' }
+      ]
+    end
+
+    desc '2 levels of nesting (GET)'
+    get '/api/:version/projects/:project_id/users' do
+      status 200
+      [
+        { id: 1, name: 'Project Member', project_id: params[:project_id].to_i, role: 'developer' }
+      ]
+    end
+
+    desc '2 levels of nesting (POST)'
+    post '/api/:version/projects/:project_id/users' do
+      status 201
+      { id: params[:user_id].to_i, project_id: params[:project_id].to_i, role: params[:role] }
+    end
+
+    desc '2 levels of nesting with different resource'
+    get '/api/:version/projects/:project_id/merge_requests' do
+      status 200
+      [
+        { id: 1, title: 'Feature update', project_id: params[:project_id].to_i, state: 'open' }
+      ]
+    end
+
+    desc '3 levels of nesting (GET)'
+    get '/api/:version/projects/:project_id/merge_requests/:merge_request_id/comments' do
+      status 200
+      [
+        { id: 1, body: 'Looks good!', merge_request_id: params[:merge_request_id].to_i }
+      ]
+    end
+
+    desc '3 levels of nesting (POST)'
+    post '/api/:version/projects/:project_id/merge_requests/:merge_request_id/comments' do
+      status 201
+      { id: 4, body: params[:body], merge_request_id: params[:merge_request_id].to_i }
+    end
+  end
+end
+# rubocop:enable API/Base
diff --git a/gems/gitlab-grape-openapi/spec/fixtures/apis/users_api.rb b/gems/gitlab-grape-openapi/spec/fixtures/apis/users_api.rb
new file mode 100644
index 0000000000000000000000000000000000000000..ebe485ef7ad72cb9f8af5b65fc1fe7f96110c974
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/fixtures/apis/users_api.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+# rubocop:disable API/Base -- Test fixture
+module TestApis
+  class UsersApi < Grape::API
+    desc 'Get all users'
+    get '/api/:version/users' do
+      status 200
+      [
+        { id: 1, name: 'John Doe', email: 'john@example.com' },
+        { id: 2, name: 'Jane Smith', email: 'jane@example.com' }
+      ]
+    end
+
+    desc 'Create a user'
+    post '/api/:version/users' do
+      status 201
+      { id: 3, name: params[:name], email: params[:email], created_at: '2025-10-20 15:55:15.465357 -0700' }
+    end
+
+    desc 'Update a user (full replacement)'
+    put '/api/:version/users/:id' do
+      status 200
+      {
+        id: params[:id].to_i,
+        name: params[:name],
+        email: params[:email],
+        updated_at: '2025-10-20 15:55:15.465357 -0700'
+      }
+    end
+
+    desc 'Update a user (partial)'
+    patch '/api/:version/users/:id' do
+      status 200
+      { id: params[:id].to_i, name: params[:name], updated_at: '2025-10-20 15:55:15.465357 -0700' }
+    end
+
+    desc 'Delete a user'
+    delete '/api/:version/users/:id' do
+      status 204
+      nil
+    end
+
+    desc 'Get user headers'
+    head '/api/:version/users/:id' do
+      status 200
+      nil
+    end
+
+    desc 'Get available options'
+    options '/api/:version/users' do
+      status 200
+      header 'Allow', 'GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS'
+      nil
+    end
+  end
+end
+# rubocop:enable API/Base
diff --git a/gems/gitlab-grape-openapi/spec/fixtures/user/person_entity.rb b/gems/gitlab-grape-openapi/spec/fixtures/entities/user/person_entity.rb
similarity index 100%
rename from gems/gitlab-grape-openapi/spec/fixtures/user/person_entity.rb
rename to gems/gitlab-grape-openapi/spec/fixtures/entities/user/person_entity.rb
diff --git a/gems/gitlab-grape-openapi/spec/fixtures/user_entity.rb b/gems/gitlab-grape-openapi/spec/fixtures/entities/user_entity.rb
similarity index 100%
rename from gems/gitlab-grape-openapi/spec/fixtures/user_entity.rb
rename to gems/gitlab-grape-openapi/spec/fixtures/entities/user_entity.rb
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/configuration_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/configuration_spec.rb
index 9682a3bfc61e4815bc43f378be5b482b1d24fb07..27865a5c4735b5c72eb22d3480016189cef8e406 100644
--- a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/configuration_spec.rb
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/configuration_spec.rb
@@ -3,17 +3,31 @@
 RSpec.describe Gitlab::GrapeOpenapi::Configuration do
   subject(:configuration) { described_class.new }
 
+  describe '#api_prefix' do
+    it 'has default value' do
+      expect(configuration.api_prefix).to eq('api')
+    end
+  end
+
+  describe '#api_prefix=' do
+    it 'sets api_prefix' do
+      configuration.api_prefix = 'internal'
+
+      expect(configuration.api_prefix).to eq('internal')
+    end
+  end
+
   describe '#api_version' do
     it 'has default value' do
-      expect(configuration.api_version).to eq('v4')
+      expect(configuration.api_version).to eq('v1')
     end
   end
 
   describe '#api_version=' do
     it 'sets api_version' do
-      configuration.api_version = 'v5'
+      configuration.api_version = 'v4'
 
-      expect(configuration.api_version).to eq('v5')
+      expect(configuration.api_version).to eq('v4')
     end
   end
 
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/operation_converter_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/operation_converter_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..843d0d52d08488eaa891d2e7f0bf024b55ab056a
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/operation_converter_spec.rb
@@ -0,0 +1,132 @@
+# frozen_string_literal: true
+
+RSpec.describe Gitlab::GrapeOpenapi::Converters::OperationConverter do
+  let(:api_prefix) { '/api' }
+  let(:api_version) { 'v1' }
+
+  def api_prefix_camelized
+    "Api#{api_version.capitalize}"
+  end
+
+  def find_route_by_method(routes, method)
+    routes.find { |r| r.instance_variable_get(:@options)[:method] == method }
+  end
+
+  def find_route_by_pattern(routes, pattern)
+    routes.find do |r|
+      r.instance_variable_get(:@pattern).instance_variable_get(:@origin) == pattern
+    end
+  end
+
+  describe '.convert' do
+    context 'with simple routes' do
+      let(:routes) { TestApis::UsersApi.routes }
+
+      context 'with GET route' do
+        subject(:operation) { described_class.convert(find_route_by_method(routes, 'GET')) }
+
+        it 'generates correct operation_id' do
+          expect(operation.operation_id).to eq("get#{api_prefix_camelized}Users")
+        end
+
+        it 'extracts description' do
+          expect(operation.description).to eq('Get all users')
+        end
+
+        it 'extracts tags' do
+          expect(operation.tags).to eq(['users'])
+        end
+      end
+
+      context 'with POST route' do
+        subject(:operation) { described_class.convert(find_route_by_method(routes, 'POST')) }
+
+        it 'generates correct operation_id' do
+          expect(operation.operation_id).to eq("post#{api_prefix_camelized}Users")
+        end
+
+        it 'extracts description' do
+          expect(operation.description).to eq('Create a user')
+        end
+
+        it 'extracts tags' do
+          expect(operation.tags).to eq(['users'])
+        end
+      end
+    end
+
+    context 'with nested routes to ensure uniqueness' do
+      let(:routes) { TestApis::NestedApi.routes }
+
+      it 'generates unique operation IDs for all routes' do
+        operation_ids = routes.map { |route| described_class.convert(route).operation_id }
+
+        expect(operation_ids).to contain_exactly(
+          "get#{api_prefix_camelized}Users",
+          "get#{api_prefix_camelized}AdminUsers",
+          "get#{api_prefix_camelized}ProjectsProjectIdUsers",
+          "get#{api_prefix_camelized}ProjectsProjectIdMergeRequests",
+          "get#{api_prefix_camelized}ProjectsProjectIdMergeRequestsMergeRequestIdComments",
+          "post#{api_prefix_camelized}ProjectsProjectIdMergeRequestsMergeRequestIdComments",
+          "post#{api_prefix_camelized}ProjectsProjectIdUsers"
+        )
+      end
+
+      it 'has no duplicate operation IDs' do
+        operation_ids = routes.map { |route| described_class.convert(route).operation_id }
+
+        expect(operation_ids.uniq.size).to eq(operation_ids.size)
+      end
+
+      context 'with /api/:version/users route' do
+        it 'generates simple operation_id' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/users")
+          operation = described_class.convert(route)
+          expect(operation.operation_id).to eq("get#{api_prefix_camelized}Users")
+        end
+      end
+
+      context 'with /api/:version/admin/users route' do
+        it 'generates operation_id with admin prefix' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/admin/users")
+          operation = described_class.convert(route)
+          expect(operation.operation_id).to eq("get#{api_prefix_camelized}AdminUsers")
+        end
+
+        it 'extracts correct tags' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/admin/users")
+          operation = described_class.convert(route)
+          expect(operation.tags).to eq(['admin'])
+        end
+      end
+
+      context 'with /api/:version/projects/:project_id/users route' do
+        it 'generates operation_id with all segments' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/projects/:project_id/users")
+          operation = described_class.convert(route)
+          expect(operation.operation_id).to eq("get#{api_prefix_camelized}ProjectsProjectIdUsers")
+        end
+
+        it 'extracts correct tags from first segment' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/projects/:project_id/users")
+          operation = described_class.convert(route)
+          expect(operation.tags).to eq(['projects'])
+        end
+      end
+
+      context 'with /api/:version/projects/:project_id/merge_requests route' do
+        it 'generates operation_id with camelized segments' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/projects/:project_id/merge_requests")
+          operation = described_class.convert(route)
+          expect(operation.operation_id).to eq("get#{api_prefix_camelized}ProjectsProjectIdMergeRequests")
+        end
+
+        it 'preserves underscores in tags' do
+          route = find_route_by_pattern(routes, "#{api_prefix}/:version/projects/:project_id/merge_requests")
+          operation = described_class.convert(route)
+          expect(operation.tags).to eq(['projects'])
+        end
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/path_converter_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/path_converter_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..2778513c6eba03be1f317dfd2a1ed1d17e80b77d
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/converters/path_converter_spec.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::GrapeOpenapi::Converters::PathConverter do
+  let(:api_prefix) { '/api' }
+  let(:api_version) { 'v1' }
+  let(:base_path) { "#{api_prefix}/#{api_version}" }
+
+  describe '.convert' do
+    let(:users_api) { TestApis::UsersApi }
+    let(:routes) { users_api.routes }
+
+    subject(:paths) { described_class.convert(routes) }
+
+    it 'groups routes by normalized path' do
+      expect(paths.keys).to eq(["#{base_path}/users", '/api/v1/users/{id}'])
+    end
+
+    it 'includes both operations' do
+      expect(paths["#{base_path}/users"].keys).to contain_exactly('get', 'options', 'post')
+    end
+
+    it 'has correct GET operation details' do
+      get_operation = paths["#{base_path}/users"]['get']
+
+      expect(get_operation[:operationId]).to eq('getApiV1Users')
+      expect(get_operation[:description]).to eq('Get all users')
+      expect(get_operation[:tags]).to eq(['users'])
+    end
+
+    it 'has correct POST operation details' do
+      post_operation = paths["#{base_path}/users"]['post']
+
+      expect(post_operation[:operationId]).to eq('postApiV1Users')
+      expect(post_operation[:description]).to eq('Create a user')
+      expect(post_operation[:tags]).to eq(['users'])
+    end
+
+    context 'with empty routes' do
+      let(:routes) { [] }
+
+      it 'returns empty hash' do
+        expect(paths).to eq({})
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/generator_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/generator_spec.rb
index 1b0f8fd78e85cc71d670acd60cec72f762665f00..5eff91eb7a9343d313c2df33becbd3114eb91cf9 100644
--- a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/generator_spec.rb
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/generator_spec.rb
@@ -1,10 +1,13 @@
 # frozen_string_literal: true
 
-RSpec.describe Gitlab::GrapeOpenapi::Generator do
-  subject(:generator) { described_class.new(api_classes, options) }
+require 'spec_helper'
 
-  let(:api_classes) { [API::TestAuditEvents] }
-  let(:options) { {} }
+RSpec.describe Gitlab::GrapeOpenapi::Generator do
+  let(:api_prefix) { '/api' }
+  let(:api_version) { 'v1' }
+  let(:base_path) { "#{api_prefix}/#{api_version}" }
+  let(:api_classes) { [TestApis::UsersApi] }
+  let(:generator) { described_class.new(api_classes) }
 
   before do
     Gitlab::GrapeOpenapi.configure do |config|
@@ -26,6 +29,8 @@
   end
 
   describe '#generate' do
+    subject(:spec) { generator.generate }
+
     it 'returns the correct keys' do
       expect(generator.generate).to include(:openapi, :info, :servers, :components, :security, :paths)
     end
@@ -38,10 +43,20 @@
       expect(generator.generate[:security]).to eq([{ 'http' => [] }])
     end
 
-    it 'executes generate_tags' do
-      generator.generate
+    it 'includes paths from API classes' do
+      expect(spec[:paths]).to have_key("#{base_path}/users")
+    end
+  end
+
+  describe '#paths' do
+    subject(:paths) { generator.paths }
+
+    it 'returns paths hash' do
+      expect(paths).to be_a(Hash)
+    end
 
-      expect(generator.tag_registry.tags.size).to eq(5)
+    it 'includes operations from API classes' do
+      expect(paths["#{base_path}/users"].keys).to contain_exactly('get', 'options', 'post')
     end
   end
 end
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/operation_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/operation_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..dbb57e42e6325105a93936d3a70d5348195974d7
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/operation_spec.rb
@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::GrapeOpenapi::Models::Operation do
+  subject(:operation) { described_class.new }
+
+  describe '#initialize' do
+    it 'initializes with empty tags array' do
+      expect(operation.tags).to eq([])
+    end
+
+    it 'initializes other fields as nil' do
+      expect(operation.operation_id).to be_nil
+      expect(operation.description).to be_nil
+    end
+  end
+
+  describe '#to_h' do
+    context 'with minimal fields' do
+      before do
+        operation.operation_id = 'getUsers'
+        operation.description = 'Get all users'
+      end
+
+      it 'includes set fields' do
+        result = operation.to_h
+
+        expect(result[:operationId]).to eq('getUsers')
+        expect(result[:description]).to eq('Get all users')
+      end
+
+      it 'omits empty tags array' do
+        result = operation.to_h
+
+        expect(result).not_to have_key(:tags)
+      end
+    end
+
+    context 'with all fields populated' do
+      before do
+        operation.operation_id = 'createUser'
+        operation.description = 'Creates a new user in the system'
+        operation.tags = %w[users admin]
+      end
+
+      it 'includes all fields' do
+        result = operation.to_h
+
+        expect(result[:operationId]).to eq('createUser')
+        expect(result[:description]).to eq('Creates a new user in the system')
+        expect(result[:tags]).to eq(%w[users admin])
+      end
+    end
+
+    context 'with tags' do
+      before do
+        operation.operation_id = 'getIssues'
+        operation.tags = ['issues']
+      end
+
+      it 'includes tags when present' do
+        result = operation.to_h
+
+        expect(result[:tags]).to eq(['issues'])
+      end
+    end
+
+    context 'with custom responses' do
+      before do
+        operation.operation_id = 'deleteUser'
+        operation.responses = {
+          '204' => { description: 'User deleted' },
+          '404' => { description: 'User not found' }
+        }
+      end
+
+      it 'uses custom responses' do
+        result = operation.to_h
+
+        expect(result[:responses]).to eq({
+          '204' => { description: 'User deleted' },
+          '404' => { description: 'User not found' }
+        })
+      end
+    end
+
+    context 'without description' do
+      before do
+        operation.operation_id = 'getProjects'
+      end
+
+      it 'omits nil description' do
+        result = operation.to_h
+
+        expect(result).not_to have_key(:description)
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/path_item_spec.rb b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/path_item_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..0eb6ea065a11746448059ce9ae2abf287dc75826
--- /dev/null
+++ b/gems/gitlab-grape-openapi/spec/gitlab/grape_openapi/models/path_item_spec.rb
@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::GrapeOpenapi::Models::PathItem do
+  subject(:path_item) { described_class.new }
+
+  describe '#initialize' do
+    it 'initializes with empty operations hash' do
+      expect(path_item.operations).to eq({})
+    end
+  end
+
+  describe '#add_operation' do
+    let(:operation) { Gitlab::GrapeOpenapi::Models::Operation.new }
+
+    before do
+      operation.operation_id = 'getUsers'
+      operation.description = 'Get all users'
+    end
+
+    it 'adds operation with lowercase method key' do
+      path_item.add_operation('GET', operation)
+
+      expect(path_item.operations['get']).to eq(operation)
+    end
+
+    it 'handles symbol method' do
+      path_item.add_operation(:post, operation)
+
+      expect(path_item.operations['post']).to eq(operation)
+    end
+
+    it 'handles already lowercase method' do
+      path_item.add_operation('delete', operation)
+
+      expect(path_item.operations['delete']).to eq(operation)
+    end
+
+    it 'adds multiple operations' do
+      get_operation = Gitlab::GrapeOpenapi::Models::Operation.new
+      get_operation.operation_id = 'getUser'
+
+      post_operation = Gitlab::GrapeOpenapi::Models::Operation.new
+      post_operation.operation_id = 'createUser'
+
+      path_item.add_operation('GET', get_operation)
+      path_item.add_operation('POST', post_operation)
+
+      expect(path_item.operations.keys).to contain_exactly('get', 'post')
+      expect(path_item.operations['get']).to eq(get_operation)
+      expect(path_item.operations['post']).to eq(post_operation)
+    end
+  end
+
+  describe '#to_h' do
+    context 'with no operations' do
+      it 'returns empty hash' do
+        expect(path_item.to_h).to eq({})
+      end
+    end
+
+    context 'with single operation' do
+      before do
+        operation = Gitlab::GrapeOpenapi::Models::Operation.new
+        operation.operation_id = 'getIssues'
+        operation.description = 'Get all issues'
+        operation.tags = ['issues']
+
+        path_item.add_operation('GET', operation)
+      end
+
+      it 'serializes operation' do
+        result = path_item.to_h
+
+        expect(result['get']).to eq({
+          operationId: 'getIssues',
+          description: 'Get all issues',
+          tags: ['issues']
+        })
+      end
+    end
+
+    context 'with multiple operations' do
+      before do
+        get_operation = Gitlab::GrapeOpenapi::Models::Operation.new
+        get_operation.operation_id = 'getUser'
+        get_operation.description = 'Get a user'
+        get_operation.tags = ['users']
+
+        post_operation = Gitlab::GrapeOpenapi::Models::Operation.new
+        post_operation.operation_id = 'createUser'
+        post_operation.description = 'Create a user'
+        post_operation.tags = ['users']
+
+        delete_operation = Gitlab::GrapeOpenapi::Models::Operation.new
+        delete_operation.operation_id = 'deleteUser'
+        delete_operation.description = 'Delete a user'
+        delete_operation.tags = ['users']
+
+        path_item.add_operation('GET', get_operation)
+        path_item.add_operation('POST', post_operation)
+        path_item.add_operation('DELETE', delete_operation)
+      end
+
+      it 'serializes all operations' do
+        result = path_item.to_h
+
+        expect(result.keys).to contain_exactly('get', 'post', 'delete')
+        expect(result['get'][:operationId]).to eq('getUser')
+        expect(result['post'][:operationId]).to eq('createUser')
+        expect(result['delete'][:operationId]).to eq('deleteUser')
+      end
+    end
+  end
+end
diff --git a/gems/gitlab-grape-openapi/spec/spec_helper.rb b/gems/gitlab-grape-openapi/spec/spec_helper.rb
index 882c676bcb76a68bcc47f23c952bf0f926e2ec9c..03c7b5d42c6e847ff1a38bd40931f73c19406a30 100644
--- a/gems/gitlab-grape-openapi/spec/spec_helper.rb
+++ b/gems/gitlab-grape-openapi/spec/spec_helper.rb
@@ -3,9 +3,11 @@
 require "gitlab-grape-openapi"
 require "grape"
 require "grape-entity"
-require "fixtures/user_entity"
-require "fixtures/user/person_entity"
 require "fixtures/test_audit_events"
+require "fixtures/entities/user_entity"
+require "fixtures/entities/user/person_entity"
+require "fixtures/apis/users_api"
+require "fixtures/apis/nested_api"
 
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure