• Rack::ETag - Automatically sets the ETag header on all String bodies.

  • Rack::JSONP - Adds JSON-P support by stripping out the callback param and padding the response with the appropriate callback format.
  • Rack::LighttpdScriptNameFix - Fixes how lighttpd sets the SCRIPTNAME and PATHINFO variables in certain configurations.
  • Rack::Locale - Detects the client locale using the Accept-Language request header and sets a rack.locale variable in the environment.
  • Rack::MailExceptions - Rescues exceptions raised from the app and sends a useful email with the exception, stacktrace, and contents of the environment.
  • Rack::PostBodyContentTypeParser - Adds support for JSON request bodies. The Rack parameter hash is populated by deserializing the JSON data provided in the request body when the Content-Type is application/json.
  • Rack::Profiler - Uses ruby-prof to measure request time.
  • Rack::Sendfile - Enables X-Sendfile support for bodies that can be served from file.
  • Rack::TimeZone - Detects the clients timezone using JavaScript and sets a variable in Rack’s environment with the offset from UTC.
  • Rack::MethodOverride - Override REQUEST_METHOD with _method post params for HTML forms.
  • Rack::Head - Drop the body of the response on HEAD requests.-
  • Rack::Deflater - gzip your responses.
  • Rack::ConditionalGet - enables conditional GET using If-None-Match and If-Modified-Since.
  • Rack::Session::Cookie and Rack::Session::Memcache - provide session management.
  • Rack::Auth::Basic - implements HTTP Basic Authentication.


  • Rack::ShowExceptions - DebugScreenのようなもの
  • Rack::Reloader
  • Rack::Lint
  • Rack::ComonnLogger