Firefox

This article is about the web browser. For other uses, see Firefox (disambiguation). "Phoenix (web browser)" redirects here. For the 1990s web browser developed at the University of Chicago, see Phoenix (tkWWW-based browser).

Firefox
Logo used since October 2019
Firefox 152.0.3 (64-bit) running on the Ubuntu operating system
Developers	Mozilla Foundation and its contributors Mozilla Corporation
Release	November 9, 2004 (2004-11-09)
Stable release(s) [±]
Standard 155.0.1  / September 4, 2026 (September 4, 2026) ESR 153 153.2.0esr  / September 1, 2026 (September 1, 2026) ESR 140 140.15.0esr / September 1, 2026 (2026-09-01) ESR 115 115.40.0esr / September 1, 2026 (2026-09-01)
Preview release(s) [±]
Beta and developer 156.0b5  / September 9, 2026 (September 9, 2026) Nightly 158.0a1  / September 10, 2026 (September 10, 2026)
Written in	C++, JavaScript, HTML, C, Rust, and others
Engines	Gecko, Quantum, and SpiderMonkey; WebKit on iOS/iPadOS
Operating system	Haiku Linux Oracle Solaris OpenIndiana macOS Catalina or later Windows 10 or later Windows Server 2016 or later Android Oreo or later iOS 15 or later iPadOS 15 or later
Included with	Various Unix-like operating systems
Available in	97 languages
Type	Web browser
License	MPL 2.0
Website	firefox.com
Repository	github.com/mozilla-firefox/firefox

Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current and anticipated web standards. The software is available for Windows, macOS, and Linux systems, as well as a mobile version for Android (see Firefox for Android) and iOS, with unofficial ports for other platforms such as Oracle Solaris and OpenIndiana.

Firefox is the spiritual successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998, before Netscape's acquisition by AOL. Firefox was created in 2002 under the codename "Phoenix" by members of the Mozilla community who desired a standalone browser rather than the Mozilla Application Suite bundle. During its beta phase, it proved to be popular with its testers and was praised for its speed, security, and add-ons compared to Microsoft's then-dominant Internet Explorer 6. It was released on November 9, 2004, and challenged Internet Explorer's dominance with 60 million downloads within nine months. In November 2017, Firefox began incorporating new technology under the code name "Quantum" to promote parallelism and a more intuitive user interface.

The current version of Firefox is available for Windows 10 or later versions of Windows, as well as macOS, and Linux. Its unofficial ports are available for various Unix systems such as Oracle Solaris and OpenIndiana, as well as for Unix-like operating systems, including FreeBSD, OpenBSD, NetBSD, and other operating systems, such as ReactOS. It is the default, pre-installed browser on Debian, Ubuntu, and some other Linux distros. Firefox is also available for Android and iOS. However, as with all other iOS web browsers, the iOS version uses the WebKit layout engine instead of Gecko due to platform requirements. An optimized version was also available on the Amazon Fire TV as one of the two main browsers available with Amazon's Silk Browser until April 30, 2021, when Firefox was discontinued on that platform.

Firefox usage share grew to a peak of 32.21% in November 2009, with Firefox 3.5 overtaking Internet Explorer 7, although not all versions of Internet Explorer as a whole; its usage then declined in competition with Google Chrome. As of July 2026, according to StatCounter, it had a 6.3% usage share on traditional PCs (i.e. as a desktop browser), making it the third-most popular PC web browser after Google Chrome (72%) and Microsoft Edge (10%), and ahead of Safari (5.2%).