Building Firefox On macOS¶
This document will help you get set up to build Firefox on your own computer. Getting set up can take a while - we need to download a lot of bytes! Even on a fast connection, this can take ten to fifteen minutes of work, spread out over an hour or two.
Memory: 4GB RAM minimum, 8GB+ recommended.
Disk Space: At least 30GB of free disk space.
Operating System: macOS - most recent or prior release. It is advisable to upgrade to the latest “point” release. See Supported Build Hosts for more information.
1. System preparation¶
1.1. Install Brew¶
Mozilla’s source tree requires a number of third-party tools. You will need to install Homebrew so that we can automatically fetch the tools we need.
1.2. Install Xcode¶
Install Xcode from the App Store. Once done, finalize the installation in your terminal:
sudo xcode-select --switch /Applications/Xcode.app sudo xcodebuild -license
1.3 Install Mercurial¶
Mozilla’s source code is hosted in Mercurial repositories. You will
need Mercurial to download and update the code. Additionally, we’ll
put user-wide python package installations on the
$PATH, so that
moz-phab will be easily accessible:
NOTE Pay special attention to the ==6.1.4, as Mercurial >=6.2 is incompatible with several plugins
echo "export PATH=\"$(python3 -m site --user-base)/bin:$PATH\"" >> ~/.zshenv python3 -m pip install --user mercurial==6.1.4
Now, restart your shell so that the
PATH change took effect.
You can test that Mercurial is installed by running:
If you’re using a shell other than
zsh, you’ll need to manually add Python’s
bin directory to your
PATH, as your shell probably won’t pick up our
2. Bootstrap a copy of the Firefox source code¶
Now that your system is ready, we can download the source code and have Firefox automatically download the other dependencies it needs. The below command will download a lot of data (years of Firefox history!) then guide you through the interactive setup process.
curl https://hg.mozilla.org/mozilla-central/raw-file/default/python/mozboot/bin/bootstrap.py -O python3 bootstrap.py
In general, the Firefox workflow works best with Mercurial. However,
if you’d prefer to use
git, you can grab the source code in
“git” form by running the bootstrap script with the
python3 bootstrap.py --vcs=git
This uses Git Cinnabar under the hood.
Choosing a build type¶
If you aren’t modifying the Firefox backend, then select one of the Artifact Mode options. If you are building Firefox for Android, you should also see the GeckoView Contributor Guide.
After finishing the bootstrap process,
bootstrap.py can be removed.
Now that your system is bootstrapped, you should be able to build!
cd mozilla-unified ./mach build ./mach run
🎉 Congratulations! You’ve built your own home-grown Firefox!
Now the fun starts¶
Time to start hacking! You should join us on Matrix, say hello in the Introduction channel, and find a bug to start working on. See the Firefox Contributors’ Quick Reference to learn how to test your changes, send patches to Mozilla, update your source code locally, and more.
macOS SDK is unsupported¶
If the SDK included with your Xcode installation is not supported by Firefox, you’ll need to manually install one that is compatible. We’re currently using the 11 SDK on our build servers, so that’s the one that you should install:
Go to the More Downloads for Apple Developers page and download Xcode 12.5.1.
Once downloaded, extract
In your terminal, copy the SDK from the installer:
mkdir -p ~/.mozbuild/macos-sdk # This assumes that Xcode is in your "Downloads" folder cp -aH ~/Downloads/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.3.sdk ~/.mozbuild/macos-sdk/
Finally, inform the Firefox build about this SDK by creating (or editing) a file called
mozconfigfile in the Firefox source code directory. Add the following line:
Now, you should be able to successfully run
“FileNotFoundError” with some stuff about _virtualenvs and site-packages¶
You likely have Python 3.10 installed (Brew or XCode may have done this – We’re not sure how it happens). There is a bug in virtualenv that prevents us from even setting up the virtual environment.
Uninstall it with the following:
brew unlink email@example.com
If you need Python 3.10, you can re-link it after the fact with
brew link firstname.lastname@example.org