Crashlytics is a free cloud-based crash-reporting service for iOS and Android applications.
It is powerful and at the same time light-weight.
Crashlytics automatically creates simple, but informative crash reports containing the code line that causes crashing of the program; and there are no needless extra lines of the code that confuse the developers and make them spend much time figuring out the root of the issue.
The reports also include detailed data about the test environment such as the device, mode in which the program crashed, etc.