Shipmate is a tool to provide dedicated developers and QA professionals access to over the air installation for iOS and Android alpha and beta apps. It is similar to TestFlight, but with less group and access ceremony, and similar to a HockeyKit standalone installation with the exception that it's built on Rails and aims to provide a bit more functionality.
Differences from TestFlight:
Differences from HockeyKit
Shipmate analyzes iOS ipa and Android apk files dropped into public/import by reading the application structure within the files. It uses the internal structure to build up a corresponding filesystem. When you load the shipmate webapp in a mobile browser, it identifies your platform and gives sideload access to imported apps.