This guide assumes you already followed the Getting Started documentation and you already downloaded mozilla-central and comm-central source code.

Install Xcode

Xcode is a prerequisite to build Firefox an you will need administrator permissions on your machine to install it. You can verify that you have these permission in System Preferences -> Users & Groups.)

Install macOS SDK headers

After installing Xcode you will find the SDK header at this location

cd /Library/Developer/CommandLineTools/SDKs/

Launch the MacOSX{your-version}.sdk (eg. MacOSX10.14.sdk) by double clicking on it and follow the installation instructions.

Bootstrap your system

Access the location where you downloaded the mozilla-central source code, most likely source/ and trigger this command:

./mach bootstrap

You will be asked to choose from the following list of options

Please choose the version of Firefox you want to build:
  1. Firefox for Desktop Artifact Mode
  2. Firefox for Desktop
  3. GeckoView/Firefox for Android Artifact Mode
  4. GeckoView/Firefox for Android

Please choose option 2 to proceed with a successful build.

This action will install all the libraries and dependencies necessary to build Thunderbird locally.

Missing libraries

It could happen that some libraries will not be installed by the bootstrap command, specifically Rust and Go. Check if these packages are available in your system by running these commands in your terminal:

• which rustc

• which cargo

If one or both commands return an empty output, you need to install them manually. We recommend using HomeBrew to download and install these packages in your system. After that, follow these steps:

• Install Rust: brew install rustc

• Install C bindings: cargo install cbindgen

export PATH=$HOME/.cargo/bin:$PATH

You're all set

Got back to the Building Thunderbird page and continue following the guide: