Building Firefox for Android

First, you’ll want to set up your machine to build Firefox. Follow the instructions there, choosing “GeckoView/Firefox for Android” as the bootstrap option.

Once you’re set up and have a GeckoView build from the above, please continue with the following steps.

1. Clone the repository and initial setup

git clone
cd firefox-android/fenix
echo dependencySubstitutions.geckoviewTopsrcdir=/path/to/mozilla-central >

replace /path/to/mozilla-central with the location of your mozilla-central/mozilla-unified source tree.

2. Build

export JAVA_HOME=$HOME/.mozbuild/jdk/jdk-17.0.6+10
export ANDROID_HOME=$HOME/.mozbuild/android-sdk-<os_name>
./gradlew clean app:assembleDebug

<os_name> is either linux, macosx or windows depending on the OS you’re building from.

For more details, check out the more complete documentation.

3. Run

From the gecko working directory:

./mach android-emulator

From the firefox-android working directory:

./gradlew :app:installFenixDebug
"$ANDROID_HOME/platform-tools/adb" shell am start -n org.mozilla.fenix.debug/org.mozilla.fenix.debug.App