Firefox

Firefox is Mozilla's popular Web browser, available for multiple platforms including Windows, OS X, and Linux on the desktop and all Android and iOS mobile devices. With broad compatibility, the latest in Web technologies, and powerful development tools, Firefox is a great choice for both Web developers and end users.

Firefox is an open source project; much of the code is contributed by our huge community of volunteers. Here you can learn about how to contribute to the Firefox project and you will also find links to information about the construction of Firefox add-ons, using the developer tools in Firefox, and other topics.

• Developer release notes

  Developer-focused release notes; learn what new capabilities for both Web sites and add-ons arrive in each version of Firefox.

• Project documentation

  Get detailed information about the internals of Firefox and its build system, so you can find your way around in the code.

• Developer guide

  Our developer guide provides details on how to get and compile the Firefox source code, how to find your way around, and how to contribute to the project.

Firefox channels

Firefox is available in five channels.

Firefox Nightly

Each night we build Firefox from the latest code in mozilla-central. These builds are for Firefox developers or those who want to try out the very latest cutting edge features while they're still under active development.

Download Firefox Nightly

Firefox Developer Edition

This is a version of Firefox tailored for developers. Every six weeks, we take the features in Firefox Nightly that are stable enough and create a new version of Firefox Developer Edition. We also add some extra features for developers that are only available in this channel.

Learn more about Firefox Developer Edition.

Download Firefox Developer Edition

Firefox Beta

After spending six weeks in Firefox Developer Edition, we take the features that are stable enough, and create a new version of Firefox Beta. Firefox Beta builds are for Firefox enthusiasts to test what's destined to become the next released Firefox version.

Download Firefox Beta

Firefox

After stabilizing for another six weeks in Beta, we're ready to ship the new features to hundreds of millions of users in a new release version of Firefox.

Download Firefox

Firefox Extended Support Release (ESR)

Firefox ESR is the long-term support edition of Firefox for desktop for use by organizations including schools, universities, businesses and others who need extended support for mass deployments.

Learn more about Firefox Extended Support Release.

Download Firefox ESR

Firefox profiles

If you find yourself using multiple Firefox channels—or just multiple configurations—on a regular basis, you should read how to use multiple Firefox profiles by turning Firefox's Profile Manager and other profile management tools to your advantage.