Devise
Flexible authentication solution for Rails with Warden
...It consists of 10 modules:
1. Authenticatable Module, responsible for password hashing and validating user authenticity when signing in
2. Omniauthable adds OmniAuth support
3. Confirmable is responsible for verifying if an account is already confirmed during sign in
4. Recoverable oversees the resetting of the user password and sends reset instructions
5. Registerable handles all aspects related to registering a new resource
6. Rememberable takes care of generating and clearing token for remembering the user from a saved cookie
7. ...