Pow Auth
Robust, modular, and extendable user authentication system
... app requires stateless tokens, the authorization layer can be replaced in minutes. Pow has been used in countless production apps and is a "batteries included" library for production. The cache backend store used for session storage can be replaced with any key-value store of your choice. The built-in Mnesia cache module works both for clusters and single-machine persistence, which can auto-connect to the cluster on startup and self-heal after netsplit.