Suitable for people with reduced awareness on Backend. Moltin - Add eCommerce to your application with a uncomplicated SDK, so you can produce a retail outlet and promote actual physical goods, no backend needed. TPInAppReceipt - Reading and Validating In App Store Receipt. Ruby Gem for Rails - Easy iTunes In-App Purchase Receipt validation, like automobile-renewable subscriptions. RMStore - A lightweight iOS library for In-App Purchases.