An authorization gem for Rails that allows you to have the complete control of your app.

An authentication and authorization system for Rails

Akamai-AuthToken is Akamai Authorization Token for Ruby 2.0+

A flexible authentication and authorization framework for Rack applications.

Users, Authorization and Authentication for Isomorfeus.

Another authorization gem

Contextual authorization for your Rails (3+) application

A command line OAuth authorization tool.

A description of a really simple authorization plugin for Rails.

Authorizr: A simple controller-centric authorization framework.

Sequel mixin for SimpleOAuth2 authorization

Lockdown is an authorization system for RubyOnRails (ver >= 2.1).

Controller level authorization

DSL-based permission rules for easy authorization logic in Rails

Cannie is a gem for authorization/permissions checking on per-controller/per-action basis.

A portable, pluggable authentication and authorization service.

PickyGuard is an opinionated authorization library.

Easy role authorization in Rails ported from an unmaintained library

Authlogic and Declarative Authorization Engine for Rails 3

A very small authorization library.