Nakama, a distributed server for social and realtime games and apps, has been released by developer Heroic Labs. The open source server features:

• Users - Register/login new users via social networks, email, or device ID.
• Storage - Store user records, settings, and other objects in collections.
• Social - Import friends via Facebook, Google, Steam and more. Users can connect with friends, and join groups. Builtin social graph to see how users can be connected.
• Chat - 1-on-1, group, and global chat between users. Persist messages for chat history.
• Multiplayer - Realtime, or turn-based active and passive multiplayer.
• Leaderboards - Dynamic, seasonal, get top members, or members around a user. Have as many as you need.
• Runtime code - Extend the server with custom logic written in Lua.
• Matchmaker, dashboard, metrics, etc, etc.

Nakama and its source code can be downloaded on GitHub at https://github.com/heroiclabs/nakama.