Helios is an open-source framework that provides essential backend services for iOS apps, from data synchronization and user accounts to push notifications, in-app purchases, and passbook integration. It allows developers to get a client-server app up-and-running in just a few minutes, and seamlessly incorporate functionality as necessary.
Getting started is easy:
$ gem install helios $ helios new myapp $ cd myapp; helios server $ open http://localhost:5000/admin
Helios is broken down into useful components, too. If you check out the .gemspec, you'll notice a few other gems that would be useful for anyone trying to build a backend service.
There's a lot of startups that do "Backend as a Service," such as Parse, so it's nice to see an OSS competitor pop up.