LeanEngine

LeanEngine is an open source project aiming at making the development of cloud-enabled mobile applications really simple, fast and fun. It consists of a pre-configured Google App Engine server and client libraries for mobile clients. It lets you focus on developing your mobile app while it handles all the boring and complicated stuff. Stuff like:

• logins (Facebook, Google, Twitter, OpenID)
• saving data to the cloud
• querying data from the cloud
• security

All this you can achieve with using LeanEngine libraries and a few lines of code on your clients. Not only that. Because it runs on your own instance of App Engine you keep total control of the data.