Mozilla projects on GitHub

Although Mozilla's major, core projects are located on the Mozilla Mercurial server, such as mozilla-central, there are a number of tools, services, and so forth whose code is hosted on GitHub. This article offers a quick guide to getting started with Mozilla code on GitHub as well as a list of many of the most interesting GitHub repositories containing Mozilla project code.

Getting started

You can look at code on GitHub without an account; that's the first thing you should know. To do more—that is, to contribute to the code or to fork it and start your own project based on Mozilla-related code—you'll need a GitHub account. You can learn more about setting up an account on the GitHub site.

Most Mozilla project code is located in repositories within the Mozilla GitHub organization. That's a great place to start looking for any projects not listed below.


This list covers the larger-scale and more important projects we have hosted on GitHub. It's not an authoritative, complete list, since it's hard to keep track of all the smaller projects that crop up (and even, at times, the large ones!). You can see a complete list of Mozilla projects on GitHub.

Project name Description
PDF.js A Portable Document Format (PDF) reader written entirely in JavaScript.
Shumway Shumway is a Flash VM and runtime written in JavaScript.
addon-sdk The Mozilla Add-on SDK.
asknot The What Can I Do For Mozilla web site, which helps you figure out how you can contribute to Mozilla.
bugsahoy A Web page to help new Mozilla contributors find bugs to work on.
bugzilla-dashboard A convenient dashboard to help you get an overview of your bugs.
codefirefox The CodeFirefox site, with videos and tutorials about how to contribute to the Firefox project and Mozilla code in general.
debugger.html The debugger.html, a modern universal JS debugger for Firefox DevTools, Node, and every other JS environment.
dxr An intelligent tool for browsing source code.
emscripten The Emscripten LLVM-to-JavaScript compiler.
fxdt-adapters The Firefox Developer Tools Adapter lets you debug various remote targets from the Firefox Developer Tools. A Web page to help new Mozilla contributors find bugs related to the Firefox Developer Tools to work on.
gecko-dev A read-only mirror of the Mercurial repositories used for Mozilla private code.
kitsune Kitsune is the platform that drives the Mozilla support web site, SUMO.
kuma The Django project that powers this site (MDN).
mdn Code samples for the MDN Web site.
mozbrick The Mozilla Brick project.
mozilla-B2G The Firefox OS project.
mozilla-appmaker The Appmaker project -- a Web tool to let non-programmers create apps.
mozilla-l10n Scripts and tools used by the localization drivers.
mozilla-metrics Tools used to collect metrics about Mozilla code.
mozilla-services Mozilla cloud services projects.
opennews The Knight-Mozilla Open News project, helping the journalism/technology community do great work through shared knowledge and code.
PluotSorbet A J2ME-compatible virtual machine written in JavaScript.
rust-lang The Rust programming language, designed for safe concurrent code.
servo The next-generation rendering engine.