< Mobile‎ | Fennec
Fennec has been replaced by Fenix. The build documentation has moved!
See the most up to date documentation at

Here is a table of contents of all the in-depth information you might need to find about Firefox for Android development.

New to the community? Welcome! Start here!



App and development overview

  • App Structure: Fennec is a combination of Java frontend code, Javascript glue and display code, and C++ rendering code. Here's a brief 9000m (30'000ft) overview of what each of those parts does.
    • Build Systems: Our app structure results in a complex build process. Moreover, we are in the process of migrating our builds from a custom (Makefile based) build, to using Gradle for the frontend/Java portions of our app. This is a brief description of our parallel build systems and what we're trying to achieve in the future.

Feature development

Test results

Build infrastructure

General developer resources

Crash Stats

  • The crash-stats page lives at
    • Be careful to select "FennecAndroid" under the product dropdown to see Firefox on Android crashes.
      • Nightly has the name XX.0a1 (e.g. 52.0a1)
      • Aurora has the name XX.0a2 (e.g. 51.0a1 - the number is one lower than nightly)
      • Beta is XX.0bN (e.g. 50.0b12). N is increased every time a new beta is released (usually weekly).
        • Note: Multiple beta versions can be listed under the versions dropdown, the first one listed might not be the currently released beta.
      • Release is XX.0.N (e.g. 49.0.2). N is increased every time there is a dot release, we usually try to avoid dot releases.
    • Beware: a single device (which potentially has a hardware issue and/or a user who has done something strange with their configuration) can result in a crash-spike on nightly, or even aurora - not every crash is something significant.
    • You can view devices that are affected by selecting a crash-signature, then going to "Aggregations", followed by clicking on the "Aggregate on" dropdown and selecting "Android device". Some issues might be device or manufacturer specific.
    • To create a bugzilla entry for a given crash, open a crash report (if you are viewing a signature, go to "reports" and click on one of the items there). From the crash report search for "Bugzilla - Report this bug in" and select the appropriate module.