Before releasing an app into the wild, it's important to stress test your app and to get user feedback when possible. To accomplish this, you need to create a signed build of your app that you can share with a group of test users. For a robust test build, you'll need two things: analytics/reporting on app performance, and a mechanism for delivery. HockeyApp provides this and more for your test builds on both iOS and Android. While both of the official platforms for releasing applications to the Apple App Store and Google Play Store provide functionality for testing and analytics, HockeyApp provides a unified place for handling these concerns, and a secondary source of metrics, crash reporting, and more.
It should be noted that HockeyApp was recently acquired by Microsoft. They have announced that the HockeyApp product will be discontinued...