What is Firefox used for?

Firefox: Source repository of Mozilla's Firefox web browser, a privacy-focused open-source browser developed by a non-profit organization. It is a good fit for contributing fixes to Firefox and studying browser engine source code.

Is Firefox open source?

Yes. Firefox is open source under a custom licence. Its source code is on GitHub at mozilla-firefox/firefox and is written mainly in JavaScript.

Yes. Firefox is open source, so the software itself is free to use under the terms of its own licence.

Can I self-host Firefox?

Yes. Firefox can be self-hosted on your own server or infrastructure.

What is Firefox an alternative to?

Firefox is an open-source alternative to Google Chrome, Microsoft Edge, Safari and Opera. Other open-source alternatives to Google Chrome include Floorp, Waterfox and Zen Browser.

Is Firefox actively maintained?

Yes. The most recent commit to Firefox was on 2 October 2026. The project has 13k stars on GitHub.

Firefox: open-source alternative to Google Chrome

About Firefox

Firefox is a web browser built by the non-profit Mozilla organization, and this is its official source repository. The project describes the browser as fast, reliable and private, and it competes with browsers from commercial vendors by being developed in the open under an organization that is not a company.

The repository is the starting point for contributors. Mozilla points developers to a Quick Reference for contributors, to the Firefox Source Docs as the primary documentation, and to Firefox Nightly for development builds. Bugs are filed on bugzilla.mozilla.org rather than in GitHub issues, and developer questions are handled on Matrix at chat.mozilla.org.

Most of the source is JavaScript, alongside lower-level code, and the code is distributed under Mozilla's open-source licenses, mainly the Mozilla Public License. Anyone can read and build the code, track development, or contribute fixes by following the documented workflow, while end users normally install released builds from the Firefox website.

Key features

Official Firefox browser source code
Firefox Source Docs for developers
Nightly development builds available
Bug tracking on Bugzilla
Developer chat on Matrix

Good fit for

→Contributing fixes to Firefox
→Studying browser engine source code

Built with: JavaScript
Tags: browser; web-browser; mozilla; privacy; open-source; javascript; firefox

Firefox: questions and answers

What is Firefox used for?: Firefox: Source repository of Mozilla's Firefox web browser, a privacy-focused open-source browser developed by a non-profit organization. It is a good fit for contributing fixes to Firefox and studying browser engine source code.
Is Firefox open source?: Yes. Firefox is open source under a custom licence. Its source code is on GitHub at mozilla-firefox/firefox and is written mainly in JavaScript.
Is Firefox free?: Yes. Firefox is open source, so the software itself is free to use under the terms of its own licence.
Can I self-host Firefox?: Yes. Firefox can be self-hosted on your own server or infrastructure.
What is Firefox an alternative to?: Firefox is an open-source alternative to Google Chrome, Microsoft Edge, Safari and Opera. Other open-source alternatives to Google Chrome include Floorp, Waterfox and Zen Browser.
Is Firefox actively maintained?: Yes. The most recent commit to Firefox was on 2 October 2026. The project has 13k stars on GitHub.