A rack middleware to output access log in ltsv format

Rack::ActionLogger is a tool to log user activity

Rack middleware for handling large file uploads. Integrates nicely with the Nginx upload module: http://www.grid.net.ru/nginx/upload.en.html

Rack Middleware for filtering by user agent

Security related HTTP headers for Rack applications

Rack middleware for using the Authorization header with token authentication

Rack::GeoIPCountry uses the geoip gem and the GeoIP database to lookup the country of a request by its IP address

A simple profiler for Rack applications, only depending on ActiveSupport::Notifications

Rack middleware that injects a message into HTML responses.

Slightly smarter session cookies for Rack 2 apps

Rack::Environmental indicates which environment your web application is running in (staging, test, etc.).

A Rack profiler for web applications.

Rack parameter validation and type coercion.

A Rack middleware to redirect IE6 users out of your website

Rack Middleware to proxy requests to a remote server. This is usefull for proxying AJAX request to remote services, thanks to @cwninja.

An extension for Rack::Attack that supports responding to throttled requests with Recaptcha tags

Rack middleware for redirecting 'www' requests, based on the original idea by trevorturk (http://trevorturk.com/2009/11/05/no-www-rack-middleware/).

Rack middleware for simplified handling of Accept header. Accept header parser.

Rescue Handler for Rack

Rack middleware for idempotency guarantees in mutating endpoints.