Firefox

Firefox 120 on Windows 11
Developer(s)	Mozilla Foundation and its contributors Mozilla Corporation
Initial release	November 9, 2004 (2004-11-09)
Stable release(s) [±]
Standard 121.0.1[1]  / January 9, 2024 (January 9, 2024) Extended Support Release 115.6.0esr[2]  / December 19, 2023 (December 19, 2023)
Preview release(s) [±]
Beta & Developer Edition 122.0b8[3]  / January 10, 2024 (January 10, 2024) Nightly 123.0a1[4]  / December 18, 2023 (December 18, 2023)
Repository	hg.mozilla.org/mozilla-central/
Written in	C++, JavaScript, HTML, C, Rust, and others[5][6]
Engines	Gecko, Quantum, and SpiderMonkey; WebKit on iOS
Operating system	Linux macOS 10.15 or later Windows 10 or later Android 5.0 or later[7] iOS 15.0 or later
Included with	Various Unix-like operating systems
Available in	97 languages[8]
Type	Web browser
License	MPL 2.0[9][10]
Website	www.mozilla.org/en-US/firefox/new/

Mozilla Firefox, or simply Firefox, is a free and open-source^[11] 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.^[12] In November 2017, Firefox began incorporating new technology under the code name "Quantum" to promote parallelism and a more intuitive user interface.^[13] Firefox is available for Windows 10 or later versions, macOS, and Linux. Its unofficial ports are available for various Unix and Unix-like operating systems, including FreeBSD,^[14] OpenBSD,^[15] NetBSD,^[16] illumos,^[17] and Solaris Unix.^[18] It 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 is also available on the Amazon Fire TV as one of the two main browsers available with Amazon's Silk Browser.^[19]

Firefox was created in 2002 under the code name "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,^[20] and challenged Internet Explorer's dominance with 60 million downloads within nine months.^[21] It is the spiritual successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998, before its acquisition by AOL.^[22]

Firefox usage share grew to a peak of 32.21% in November 2009,^[23] with Firefox 3.5 overtaking Internet Explorer 7, although not all versions of Internet Explorer as a whole;^[24][25] its usage then declined in competition with Google Chrome.^[23] As of December 2023, according to StatCounter, it had a 6.7% usage share on traditional PCs (i.e. as a desktop browser), making it the fourth-most popular PC web browser after Google Chrome (62%), Safari (13%), and Microsoft Edge (11%).^[26][27]

History

The project began as an experimental branch of the Mozilla project by Dave Hyatt, Joe Hewitt, and Blake Ross. They believed the commercial requirements of Netscape's sponsorship and developer-driven feature creep compromised the utility of the Mozilla browser.^[28] To combat what they saw as the Mozilla Suite's software bloat, they created a standalone browser, with which they intended to replace the Mozilla Suite.^[29] Version 0.1 was released on September 23, 2002.^[30] On April 3, 2003, the Mozilla Organization announced that it planned to change its focus from the Mozilla Suite to Firefox and Thunderbird.^[31]

Screenshot of Phoenix 0.1 on Windows XP

The Firefox project has undergone several name changes.^[32] The nascent browser was originally named Phoenix, after the mythical bird that rose triumphantly from the ashes of its dead predecessor (in this case, from the "ashes" of Netscape Navigator, after it was sidelined by Microsoft Internet Explorer in the "First Browser War"). Phoenix was renamed in 2003 due to a trademark claim from Phoenix Technologies. The replacement name, Firebird, provoked an intense response from the Firebird database software project.^[33][34] The Mozilla Foundation reassured them that the browser would always bear the name Mozilla Firebird to avoid confusion. After further pressure, Mozilla Firebird became Mozilla Firefox on February 9, 2004.^[35] The name Firefox was said to be derived from a nickname of the red panda,^[36] which became the mascot for the newly named project.^[37] For the abbreviation of Firefox, Mozilla prefers Fx or fx, although it is often abbreviated as FF.^[38]

The Firefox project went through many versions before version 1.0 and had already gained a great deal of acclaim from numerous media outlets, such as Forbes^[39] and The Wall Street Journal.^[40] Among Firefox's popular features were the integrated pop-up blocker, tabbed browsing, and an extension mechanism for adding functionality. Although these features have already been available for some time in other browsers such as the Mozilla Suite and Opera, Firefox was the first of these browsers to have achieved large-scale adoption. Firefox attracted attention as an alternative to Internet Explorer, which had come under fire for its alleged poor program design and insecurity—detractors cite IE's lack of support for certain Web standards, use of the potentially dangerous ActiveX component, and vulnerability to spyware and malware installation. Microsoft responded by releasing Windows XP Service Pack 2, which added several important security features to Internet Explorer 6.^[41]

Version 1.0 of Firefox was released on November 9, 2004.^[42] This was followed by version 1.5 in November 2005, version 2.0 in October 2006, version 3.0 in June 2008, version 3.5 in June 2009, version 3.6 in January 2010, and version 4.0 in March 2011. From version 5 onwards, the development and release model changed into a "rapid" one; by the end of 2011 the stable release was version 9, and by the end of 2012 it reached version 17.^[43]

Major redesigns of its graphical user interface occurred on versions 4.0 (Strata) in March 2011, 29.0 (Australis) in April 2014, 57.0 (Photon) in November 2017, and 89.0 (Proton) in June 2021.

In 2016, Mozilla announced a project known as Quantum, which sought to improve Firefox's Gecko engine and other components to improve the browser's performance, modernize its architecture, and transition the browser to a multi-process model. These improvements came in the wake of decreasing market share to Google Chrome, as well as concerns that its performance was lapsing in comparison. Despite its improvements, these changes required existing add-ons for Firefox to be made incompatible with newer versions, in favor of a new extension system that is designed to be similar to Chrome and other recent browsers. Firefox 57, which was released in November 2017, was the first version to contain enhancements from Quantum, and has thus been named Firefox Quantum. A Mozilla executive stated that Quantum was the "biggest update" to the browser since version 1.0.^[44][45][46] Unresponsive and crashing pages only affect other pages loaded within the same process. While Chrome uses separate processes for each loaded tab, Firefox distributes tabs over four processes by default (since Quantum), in order to balance memory consumption and performance. The process count can be adjusted, where more processes increase performance at the cost of memory, therefore suitable for computers with larger RAM capacity.^[47][48]

On May 3, 2019, the expiration of an intermediate signing certificate on Mozilla servers caused Firefox to automatically disable and lock all browser extensions (add-ons).^[49][50] Mozilla began the roll-out of a fix shortly thereafter, using their Mozilla Studies component.^[49][50]

Support for Adobe Flash was dropped on January 6, 2021, with the release of Firefox 85. ^[51]

On January 13, 2022, an issue with Firefox's HTTP/3 implementation resulted in a widespread outage for multiple hours.^[52]

Features

Features of the desktop edition include tabbed browsing, full-screen mode, spell checking, incremental search, smart bookmarks, bookmarking and downloading through drag and drop,^[53][54] a download manager, user profile management,^[55] private browsing, bookmark tags, bookmark exporting,^[56] offline mode,^[57] a screenshot tool, web development tools, a "page info" feature which shows a list of page metadata and multimedia items,^[58] a sophisticated configuration menu at about:config for power users, and more location-aware browsing (also known as "geolocation") based on a Google service.^[59] Firefox has an integrated search system which uses Google by default in most markets but an update for American users in 2021 made it start including paid promotions by default in its suggestions.^[60][61] DNS over HTTPS is another feature whose default behaviour is determined geographically.^[62]

Firefox provides an environment for web developers in which they can use built-in tools, such as the Error Console or the DOM Inspector, and extensions, such as Firebug and more recently there has been an integration feature with Pocket. Firefox Hello was an implementation of WebRTC, added in October 2014, which allows users of Firefox and other compatible systems to have a video call, with the extra feature of screen and file sharing by sending a link to each other. Firefox Hello was scheduled to be removed in September 2016.^[63]

Former features include a File Transfer Protocol (FTP) client for browsing file servers, the ability to block images from individual domains (until version 72),^[64] a 3D page inspector (versions 11 to 46), tab grouping (until version 44), and the ability to add customized extra toolbars (until version 28).^[65][66][67]

Standards

The result of the Acid3 test on Firefox 17

Firefox implements many web standards, including HTML4 (almost full HTML5), XML, XHTML, MathML, SVG 1.1 (full),^[77] SVG 2 (partial),^[78][79] CSS (with extensions),^[80] ECMAScript (JavaScript), DOM, XSLT, XPath, and APNG (Animated PNG) images with alpha transparency.^[81] Firefox also implements standards proposals created by the WHATWG such as client-side storage,^[82][83] and the canvas element.^[84] These standards are implemented through the Gecko layout engine, and SpiderMonkey JavaScript engine. Firefox 4 was the first release to introduce significant HTML5 and CSS3 support.

Firefox has passed the Acid2 standards-compliance test since version 3.0.^[85] Mozilla had originally stated that they did not intend for Firefox to pass the Acid3 test fully because they believed that the SVG fonts part of the test had become outdated and irrelevant, due to WOFF being agreed upon as a standard by all major browser makers.^[86] Because the SVG font tests were removed from the Acid3 test in September 2011, Firefox 4 and greater scored 100/100.^[87][88]

Firefox also implements "Safe Browsing,"^[89] a proprietary protocol^[90] from Google used to exchange data related with phishing and malware protection.

Firefox supports the playback of video content protected by HTML5 Encrypted Media Extensions (EME), since version 38. For security and privacy reasons, EME is implemented within a wrapper of open-source code that allows execution of a proprietary DRM module by Adobe Systems—Adobe Primetime Content Decryption Module (CDM). CDM runs within a "sandbox" environment to limit its access to the system and provide it a randomized device ID to prevent services from uniquely identifying the device for tracking purposes. The DRM module, once it has been downloaded, is enabled, and disabled in the same manner as other plug-ins. Since version 47,^[91] "Google's Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video" is also supported. Mozilla justified its partnership with Adobe and Google by stating:

Firefox downloads and enables the Adobe Primetime and Google Widevine CDMs by default to give users a smooth experience on sites that require DRM. Each CDM runs in a separate container called a sandbox and you will be notified when a CDM is in use. You can also disable each CDM and opt-out of future updates

— Watch DRM content on Firefox^[92]

and that it is "an important step on Mozilla's roadmap to remove NPAPI plugin support."^[93] Upon the introduction of EME support, builds of Firefox on Windows were also introduced that exclude support for EME.^[94][95] The Free Software Foundation and Cory Doctorow condemned Mozilla's decision to support EME.^[96]

Security

Firefox allowed for a sandbox security model to manage privileges accorded to JavaScript code, but that feature has since been deprecated.^[97] It limits scripts from accessing data from other websites based on the same-origin policy.^[98] It also provides support for smart cards to web applications, for authentication purposes.^[99] It uses TLS to protect communications with web servers using strong cryptography when using the HTTPS protocol.^[100] The freely available HTTPS Everywhere add-on enforces HTTPS, even if a regular HTTP URL is entered. Firefox now supports HTTP/2.^[101]

The Mozilla Foundation offers a "bug bounty" (US$3,000 to US$7,500 cash reward) to researchers who discover severe security holes in Firefox.^[102] Official guidelines for handling security vulnerabilities discourage early disclosure of vulnerabilities so as not to give potential attackers an advantage in creating exploits.^[103]

Because Firefox generally has fewer publicly known security vulnerabilities than Internet Explorer (see Comparison of web browsers), improved security is often cited as a reason to switch from Internet Explorer to Firefox.^{[104][105][106][107]} The Washington Post reported that exploit code for known critical security vulnerabilities in Internet Explorer was available for 284 days in 2006. In comparison, exploit code for known, critical security vulnerabilities in Firefox was available for nine days before Mozilla issued a patch to remedy the problem.^[108]

A 2006 Symantec study showed that, although Firefox had surpassed other browsers in the number of vendor-confirmed vulnerabilities that year through September, these vulnerabilities were patched far more quickly than those found in other browsers, with Firefox's vulnerabilities being fixed on average one day after the exploit code was made available, as compared to nine days for Internet Explorer.^[109] Symantec later clarified their statement, saying that Firefox still had fewer security vulnerabilities than Internet Explorer, as counted by security researchers.^[110]

In October 2009, Microsoft's security engineers acknowledged that Firefox was vulnerable to a security issue found in the 'Windows Presentation Foundation' browser plug-in since February of that year. A .NET Framework 3.5 SP1 Windows Update had silently installed the vulnerable plug-in into Firefox.^[111] This vulnerability has since been patched by Microsoft.^[112]

In 2010, a study of the National Institute of Standards and Technology (NIST), based on data compiled from the National Vulnerability Database (NVD), Firefox was listed as the fifth-most vulnerable desktop software, with Internet Explorer as the eighth, and Google Chrome as the first.^[113]

InfoWorld has cited security experts saying that, as Firefox becomes more popular, more vulnerabilities will be found,^[114] a claim that Mitchell Baker, president of the Mozilla Foundation, has denied. "There is this idea that market share alone will make you have more vulnerabilities. It is not relational at all," she said.^[115]

As of February 11, 2011, Firefox 3.6 had no known unpatched security vulnerabilities according to Secunia.^[116] Internet Explorer 8 had five unpatched security vulnerabilities; the worst being rated "Less Critical" by Secunia.^[117] Mozilla claims that all patched vulnerabilities of Mozilla products are publicly listed.^[118]

Firefox 11, released in January 2012, introduced a 3D page inspector that visualizes web pages' document object model three-dimensionally through WebGL. The feature was accessible from the developer tools.^[119]

On January 28, 2013, Mozilla was recognized as the most trusted internet company for privacy in 2012.^[120] This study was performed by the Ponemon Institute and was a result of a survey from more than 100,000 consumers in the United States.

In February 2013, plans were announced for Firefox 22 to disable third-party cookies by default. However, the introduction of the feature was then delayed so Mozilla developers could "collect and analyze data on the effect of blocking some third-party cookies." Mozilla also collaborated with Stanford University's "Cookie Clearinghouse" project to develop a blacklist and whitelist of sites that will be used in the filter.^[121][122]

Version 23, released in August 2013, followed the lead of its competitors by blocking iframe, stylesheet, and script resources served from non-HTTPS servers embedded on HTTPS pages by default. Additionally, JavaScript could also no longer be disabled through Firefox's preferences, and JavaScript was automatically re-enabled for users who upgraded to 23 or higher with it disabled. The change was made due to its use across the majority of websites, the potential repercussions on inexperienced users who are unaware of its impact, along with the availability of extensions such as NoScript, which can disable JavaScript in a more controlled fashion. The following release added the ability to disable JavaScript through the developer tools for testing purposes.^{[123][124][125]}

In January 2015, TorrentFreak reported that using Firefox when connected to the internet using a VPN can be a serious security issue due to the browser's support for WebRTC.^[126]

Beginning with Firefox 48, all extensions must be signed by Mozilla to be used in release and beta versions of Firefox. Firefox 43 blocked unsigned extensions but allowed enforcement of extension signing to be disabled. All extensions must be submitted to Mozilla Add-ons and be subject to code analysis in order to be signed, although extensions do not have to be listed on the service to be signed.^[127][128] On May 2, 2019, Mozilla announced that it would be strengthening the signature enforcement with methods that included the retroactive disabling of old extensions now deemed to be insecure. A Firefox update on May 3 led to bug reports about all extensions being disabled. This was found to be the result of an overlooked certificate and not the policy change set to go into effect on June 10.^[129]

In Firefox versions prior to 7.0, an information bar appears on the browser's first start asking users whether they would like to send performance statistics, or "telemetry", to Mozilla. It is enabled by default in development versions of Firefox, but not in release versions.^[130] According to Mozilla's privacy policy,^[131] these statistics are stored only in aggregate format, and the only personally identifiable information transmitted is the user's IP address.

In November 2018, Firefox began using a sandbox to isolate web tabs from each other and from the rest of the system. Its lack of such a feature had previously earned it negative comparisons with Google Chrome and Microsoft Edge.^[132][133]

Since version 60 Firefox includes the option to use DNS over HTTPS (DoH), which causes DNS lookup requests to be sent encrypted over the HTTPS protocol. To use this feature the user must set certain preferences beginning with "network.trr" (Trusted Recursive Resolver) in about:config: if network.trr.mode is 0, DoH is disabled; 1 activates DoH in addition to unencrypted DNS; 2 causes DoH to be used before unencrypted DNS; to use only DoH, the value must be 3. By setting network.trr.uri to the URL, special Cloudflare servers will be activated.^[134][135] Mozilla has a privacy agreement with this server host that restricts their collection of information about incoming DNS requests.^[136]

On May 21, 2019, Firefox was updated to include the ability to block scripts that used a computer's CPU to mine cryptocurrency without a user's permission, in Firefox version 67.0. The update also allowed users to block known fingerprinting scripts that track their activity across the web, however it does not resist fingerprinting on its own.^[137]

On July 2, 2019, Mozilla introduced a mechanism to allow Firefox to automatically trust OS-installed certificates to prevent TLS errors.^[138]

In October 2019, ZDNet reported Firefox version 68 ESR passed all minimum requirements for mandatory security features during an exam by the Federal Office for Information Security of Germany.^[139]

In Mozilla Foundation Security Advisory 2020–03, the company reported that the CVE-2019-17026 vulnerability (type confusion vulnerability in IonMonkey) had been detected in the wild and was being actively exploited.^[140][141]

In March 2021, Firefox launched SmartBlock in version 87 to offer protection against cross-site tracking, without breaking the websites users visit.^[142] Also known as state partitioning or "total cookie protection", works via a feature in the browser that isolates data from each site visited by the user to ensure that cross-site scripting is very difficult if not impossible. The feature also isolates local storage, service workers and other common ways for sites to store data.^[143]

Localizations

Firefox is a widely localized web browser. The first official release in November 2004 was available in 24 different languages and for 28 locales, including British English, American English, European Spanish, Argentine Spanish, Chinese in Traditional Chinese characters and Simplified Chinese characters and in Bangla.^[144] As of January 2024, currently supported versions 121.0.1 and 115.6.0esr are available in 97 locales (88 languages).^[8]

Platform availability

The desktop version of Firefox is available and supports Microsoft Windows, macOS, and Linux, while Firefox for Android is available for Android (formerly Firefox for mobile, it also ran on Maemo, MeeGo and Firefox OS) and Firefox for iOS is available for iOS. Smartphones that support Linux but do not support Android or iOS apps can also run Firefox in its desktop version, for example using postmarketOS.

Operating system		Latest stable version	Support status
Windows	10 v1709 or later	Current stable version: 121.0.1 (ARM64)[1]	2017–
		Older version, yet still maintained: 115.6.0esr (ARM64)[2]
	10 or later, Server 2016 or later	Current stable version: 121.0.1 (x64)[1]	2015–
		Older version, yet still maintained: 115.6.0esr (x64)[2]
		Current stable version: 121.0.1 (IA-32)[1]
		Older version, yet still maintained: 115.6.0esr (IA-32)[2]
	7, Server 2008 R2, 8, Server 2012, 8.1 and Server 2012 R2	Older version, yet still maintained: 115.6.0esr (x64)[2]	2015–2024
		Older version, yet still maintained: 115.6.0esr (IA-32)[2]	2009–2024
		Old version, no longer maintained: 115.0.2 (x64)[145]	2015–2023
		Old version, no longer maintained: 115.0.2 (IA-32)[145]	2009–2023
	XP SP2+, Server 2003 SP1+ & R2, Vista and Server 2008	Old version, no longer maintained: 52.9.0esr (IA-32)[146]	2004–2018
		Old version, no longer maintained: 52.0.2 (IA-32)[147][148]	2004–2017
	2000, XP RTM–SP1 and Server 2003 RTM	Old version, no longer maintained: 10.0.12esr[149]	2004–2013
		Old version, no longer maintained: 12.0[150][151][152]	2004–2012
	NT 4.0 (IA-32), 98 and ME	Old version, no longer maintained: 2.0.0.20[153]	2004–2008
	95	Old version, no longer maintained: 1.5.0.12	2004–2007
macOS	11 (ARM64) or later	Current stable version: 121.0.1[1] [154]	2020–
		Older version, yet still maintained: 115.6.0esr[2]
	10.15 (x64) or later	Current stable version: 121.0.1[1]	2019–
		Older version, yet still maintained: 115.6.0esr[2]
	10.12–10.14	Older version, yet still maintained: 115.6.0esr[2]	2016–2024
		Old version, no longer maintained: 115.0.2[155]	2016–2023
	10.9–10.11	Old version, no longer maintained: 78.15.0esr[156]	2013–2021
		Old version, no longer maintained: 78.0.2[157][158]	2013–2020
	10.6–10.8	Old version, no longer maintained: 45.9.0esr[159]	2009–2017
		Old version, no longer maintained: 48.0.2[160][161][162][163]	2009–2016
	10.5 (IA-32 and x64)	Old version, no longer maintained: 10.0.12esr[149]	2007–2013
		Old version, no longer maintained: 16.0.2[164]	2007–2012
	10.4 (IA-32 and PPC)–10.5 (PPC)	Old version, no longer maintained: 3.6.28[165]	2005–2012
	10.2–10.3	Old version, no longer maintained: 2.0.0.20[153]	2004–2008
	10.0–10.1	Old version, no longer maintained: 1.0.8	2004–2006
Linux desktop		Current stable version: 121.0.1 (x64)[1]	2011–
		Older version, yet still maintained: 115.6.0esr (x64)[2]
		Current stable version: 121.0.1 (IA-32)[1]	2004–
		Older version, yet still maintained: 115.6.0esr (IA-32)[2]

Notes

• In March 2014, the Windows Store app version of Firefox was cancelled, although there is a beta release.^[166]
• SSE2 instruction set support is required for 49.0 or later for Windows and 53.0 or later for Linux, IA-32 support only applies to superscalar processors.

Firefox source code may be compiled for various operating systems; however, officially distributed binaries are provided for the following:

macOS

Firefox 57 on macOS High Sierra

The first official release (Firefox version 1.0) supported macOS (then called Mac OS X) on the PowerPC architecture. Mac OS X builds for the IA-32 architecture became available via a universal binary which debuted with Firefox 1.5.0.2 in 2006.

Starting with version 4.0, Firefox was released for the x64 architecture to which macOS had migrated.^[179] Version 4.0 also dropped support for PowerPC architecture, although other projects continued development of a PowerPC version of Firefox.^[180]

Firefox was originally released for Mac OS X 10.0 and higher.^[181] The minimum OS then increased to Mac OS X 10.2 in Firefox 1.5 and 10.4 in Firefox 3.^[182][183] Firefox 4 dropped support for Mac OS X 10.4 and PowerPC Macs, and Firefox 17 dropped support for Mac OS X 10.5 entirely.^[184][185] The system requirements were left unchanged until 2016, when Firefox 49 dropped support for Mac OS X 10.6–10.8.^[186][187] Mozilla ended support for OS X 10.9–10.11 in Firefox 79, with those users being supported on the Firefox 78 ESR branch until November 2021.^{[188][189][190]} Most recently, Mozilla ended support for macOS 10.12–10.14 in Firefox 116, with those users being supported on the Firefox 115 ESR branch until late 2024.

Linux

Firefox 96 on Arch Linux

Since its inception, Firefox for Linux supported the 32-bit memory architecture of the IA-32 instruction set. 64-bit builds were introduced in the 4.0 release.^[179] The 46.0 release replaced GTK 2.18 with 3.4 as a system requirement on Linux and other systems running X.Org.^[191] Starting with 53.0, the 32-bit builds require the SSE2 instruction set. Firefox also can run on number of other architectures on Linux, including ARM, AArch64, POWER/PowerPC/Power ISA, SPARC, PA-RISC, MIPS, s390, and in the past Alpha, IA-64 (Intel Itanium) and m68k.

Firefox for Android

Main article: Firefox for Android

Firefox for mobile, codenamed "Fennec", was first released for Maemo in January 2010 with version 1.0^[192] and for Android in March 2011 with version 4.0.^[193] Support for Maemo was discontinued after version 7, released in September 2011.^[194] Fennec had a user interface optimized for phones and tablets. It included the Awesome Bar, tabbed browsing, add-on support, a password manager, location-aware browsing, and the ability to synchronize with the user's other devices with Mozilla Firefox using Firefox Sync.^[195] It was criticized for being slow,^[196] however, in part due to its poor port of Gecko.^[197] At the end of its existence, it had a market share of 0.5% on Android.^[198]

In August 2020, Mozilla launched a new version of its Firefox for Android app, named Firefox Daylight to the public^[199] and codenamed Fenix,^[200] after a little over a year of testing.^[197] It boasted higher speeds with its new GeckoView engine, which is described as being "the only independent web engine browser available on Android". It also added Enhanced Tracking Protection 2.0, a feature that blocks many known trackers on the Internet.^[201] It also added the ability to place the address bar on the bottom, and a new Collections feature.^[199] However, it was criticized for only having nine Add-ons at launch, and missing certain features.^{[202][203][204]} In response, Mozilla stated that they will allow more Add-ons with time.^[205]

Firefox on MeeGo OS

Firefox on Firefox OS

Firefox 115 on Android

Operating system		Latest stable version	Support status
Android (including Android-x86)	5.0 or later	Current stable version: 121.0 (x64)[206]	2018–
		Current stable version: 121.0 (ARM64)[206]	2017–
		Current stable version: 121.0 (IA-32 and ARMv7)[206]	2014–
	4.1–4.4	Old version, no longer maintained: 68.11.0 (x64)[207]	2018–2020
		Old version, no longer maintained: 68.11.0 (IA-32)	2013–2020
		Old version, no longer maintained: 68.11.0 (ARMv7)	2012–2020
	4.0	Old version, no longer maintained: 55.0.2 (IA-32)[208][209]	2013–2017
		Old version, no longer maintained: 55.0.2 (ARMv7)	2011–2017
	3.0–3.2	Old version, no longer maintained: 45.0.2 (ARMv7)[208]	2011–2016
	2.3	Old version, no longer maintained: 47.0 (ARMv7)[208][210]
	2.2–4.3	Old version, no longer maintained: 31.3.0esr (ARMv6)	2012–2015
	2.2	Old version, no longer maintained: 31.0 (ARMv7)[211]	2011–2014
	2.1	Old version, no longer maintained: 19.0.2 (ARMv6)	2012–2013
		Old version, no longer maintained: 19.0.2 (ARMv7)	2011–2013
	2.0	Old version, no longer maintained: 6.0.2 (ARMv7)	2011
Firefox OS	2.2	Old version, no longer maintained: 35/36/37	2015
	2.1	Old version, no longer maintained: 33/34	2014–2015
	2.0	Old version, no longer maintained: 31/32
Maemo		Old version, no longer maintained: 7.0.1	2010–2011
Windows Mobile	6.x	Old version, no longer maintained: 1.0a3	2009–2010

Legend:

Old version

Older version, still maintained

Latest version

Latest preview version

Future release

Notes

• Firefox for iOS is not listed in this table as its version numbers would be misleading. Prior to version 96^[212] it used version numbers that do not correspond to any of the other Firefox versions. Those share a core component, the Gecko rendering engine, and track its version numbers, whereas the version for the iOS operating system uses the operating system's rendering engine (WebKit), rather than Mozilla's (Gecko).

Channels and release schedule

In March 2011, Mozilla presented plans to switch to a faster 16-week development cycle, similar to Google Chrome. Ars Technica noted that this new cycle entailed "significant technical and operational challenges" for Mozilla (notably preserving third-party add-on compatibility), but that it would help accelerate Firefox's adoption of new web standards, feature, and performance improvements.^[246][247] This plan was implemented in April 2011.^[248] The release process was split into four "channels", with major releases trickling down to the next channel every six to eight weeks. For example, the nightly channel would feature a preliminary unstable version of Firefox 6, which would move to the experimental "Aurora" channel after preliminary testing, then to the more stable "beta" channel, before finally reaching the public release channel, with each stage taking around six weeks.^{[249][246][250]} For corporations, Mozilla introduced an Extended Support Release channel, with new versions released every 30 weeks (and supported for 12 more weeks after a new ESR version is released), though Mozilla warned that it would be less secure than the release channel, since security patches would only be backported for high-impact vulnerabilities.^[251][252]

In 2017, Mozilla abandoned the Aurora channel, which saw low uptake, and rebased Firefox Developer Edition onto the beta channel.^[253] Mozilla uses A/B testing^[254] and a staged rollout mechanism for the release channel, where updates are first presented to a small fraction of users, with Mozilla monitoring its telemetry for increased crashes or other issues before the update is made available to all users.^[249] In 2020, Firefox moved to a four-week release cycle, to catch up with Chrome in support for new web features.^[255][256] Chrome switched to a four-week cycle a year later.^[257]

Licensing

Firefox source code is free software, with most of it being released under the Mozilla Public License (MPL) version 2.0.^[10] This license permits anyone to view, modify, or redistribute the source code. As a result, several publicly released applications have been built from it, such as Netscape, Flock, Miro, GNU IceCat, Iceweasel, Songbird, Pale Moon, Waterfox, and Comodo IceDragon.

In the past, Firefox was licensed solely under the MPL, then version 1.1,^[258] which the Free Software Foundation criticized for being weak copyleft, as the license permitted, in limited ways, proprietary derivative works. Additionally, code only licensed under MPL 1.1 could not legally be linked with code under the GPL.^[259][260] To address these concerns, Mozilla re-licensed most of Firefox under the tri-license scheme of MPL 1.1, GPL 2.0, or LGPL 2.1. Since the re-licensing, developers were free to choose the license under which they received most of the code, to suit their intended use: GPL or LGPL linking and derivative works when one of those licenses is chosen, or MPL use (including the possibility of proprietary derivative works) if they chose the MPL.^[258] However, on January 3, 2012, Mozilla released the GPL-compatible MPL 2.0,^[261] and with the release of Firefox 13 on June 5, 2012, Mozilla used it to replace the tri-licensing scheme.^[262]

The crash reporting service was initially closed-source but switched with version 3 from a program called Talkback to the open-source Breakpad (and Socorro server).

Trademark and logo

The name "Mozilla Firefox" is a registered trademark of Mozilla; along with the official Firefox logo, it may only be used under certain terms and conditions. Anyone may redistribute the official binaries in unmodified form and use the Firefox name and branding for such distribution, but restrictions are placed on distributions which modify the underlying source code.^[263] The name "Firefox" derives from a nickname of the red panda.^[37]

Mozilla has placed the Firefox logo files under open-source licenses,^[264][265] but its trademark guidelines do not allow displaying altered^[266] or similar logos^[267] in contexts where trademark law applies.

Logo used for Iceweasel

There has been some controversy over the Mozilla Foundation's intentions in stopping certain open-source distributions from using the "Firefox" trademark.^[11] Open-source browsers "enable greater choice and innovation in the market rather than aiming for mass-market domination."^[268] Mozilla Foundation Chairperson Mitchell Baker explained in an interview in 2007 that distributions could freely use the Firefox trademark if they did not modify source code, and that the Mozilla Foundation's only concern was with users getting a consistent experience when they used "Firefox".^[269]

To allow distributions of the code without using the official branding, the Firefox build system contains a "branding switch". This switch, often used for alphas ("Auroras") of future Firefox versions, allows the code to be compiled without the official logo and name and can allow a derivative work unencumbered by restrictions on the Firefox trademark to be produced. In the unbranded build, the trademarked logo and name are replaced with a freely distributable generic globe logo and the name of the release series from which the modified version was derived.

Distributing modified versions of Firefox under the "Firefox" name required explicit approval from Mozilla for the changes made to the underlying code, and required the use of all of the official branding. For example, it was not permissible to use the name "Firefox" without also using the official logo. When the Debian project decided to stop using the official Firefox logo in 2006 (because Mozilla's copyright restrictions at the time were incompatible with Debian's guidelines), they were told by a representative of the Mozilla Foundation that this was not acceptable and was asked either to comply with the published trademark guidelines or cease using the "Firefox" name in their distribution.^[270] Debian switched to branding their modified version of Firefox "Iceweasel" (but in 2016 switched back to Firefox), along with other Mozilla software. GNU IceCat is another derived version of Firefox distributed by the GNU Project, which maintains its separate branding.^[271]

Promotion

Firefox mascot at the FISL 16 (2015), Brazil

Firefox was adopted rapidly, with 100 million downloads in its first year of availability.^[279] This was followed by a series of aggressive marketing campaigns starting in 2004 with a series of events Blake Ross and Asa Dotzler called "marketing weeks".^[280]

Firefox continued to heavily market itself by releasing a marketing portal dubbed "Spread Firefox" (SFX) on September 12, 2004,^[281] It debuted along with the Firefox Preview Release, creating a centralized space for the discussion of various marketing techniques. The release of their manifesto stated that "the Mozilla project is a global community of people who believe that openness, innovation and opportunity are key to the continued health of the Internet."^[268] A two-page ad in the edition of December 16 of The New York Times, placed by Mozilla Foundation in coordination with Spread Firefox, featured the names of the thousands of people worldwide who contributed to the Mozilla Foundation's fundraising campaign to support the launch of the Firefox 1.0 web browser.^[282] SFX portal enhanced the "Get Firefox" button program, giving users "referrer points" as an incentive. The site lists the top 250 referrers. From time to time, the SFX team or SFX members launch marketing events organized at the Spread Firefox website. As a part of the Spread Firefox campaign, there was an attempt to break the world download record with the release of Firefox 3.^[283] This resulted in an official certified Guinness world record, with over eight million downloads.^[284] In February 2011, Mozilla announced that it would be retiring Spread Firefox (SFX). Three months later, in May 2011, Mozilla officially closed Spread Firefox. Mozilla wrote that "there are currently plans to create a new iteration of this website [Spread Firefox] at a later date."^[285]

In celebration of the third anniversary of the founding of the Mozilla Foundation, the "World Firefox Day" campaign was established on July 15, 2006,^[286][287] and ran until September 15, 2006.^[288] Participants registered themselves and a friend on the website for nomination to have their names displayed on the Firefox Friends Wall, a digital wall that was displayed at the headquarters of the Mozilla Foundation.

The Firefox community has also engaged in the promotion of their web browser. In 2006, some of Firefox's contributors from Oregon State University made a crop circle of the Firefox logo in an oat field near Amity, Oregon, near the intersection of Lafayette Highway and Walnut Hill Road.^[289] After Firefox reached 500 million downloads on February 21, 2008, the Firefox community celebrated by visiting Freerice to earn 500 million grains of rice.^[290]

Other initiatives included Live Chat – a service Mozilla launched in 2007 that allowed users to seek technical support from volunteers.^[291] The service was later retired.^[292]

To promote the launch of Firefox Quantum in November 2017, Mozilla partnered with Reggie Watts to produce a series of TV ads and social media content.^[293]

Performance

Usage share

Usage share of web browsers according to StatCounter

Downloads have continued at an increasing rate since Firefox 1.0 was released on November 9, 2004, and as of 31 July 2009 Firefox had already been downloaded over one billion times.^[317] This number does not include downloads using software updates or those from third-party websites.^[318] They do not represent a user count, as one download may be installed on many machines, one person may download the software multiple times, or the software may be obtained from a third-party.

In July 2010, IBM asked all employees (about 400,000) to use Firefox as their default browser.^[319]

Firefox was the second-most used web browser until November 2011, when Google Chrome surpassed it.^[320] According to Mozilla, Firefox had more than 450 million users as of October 2012.^[321][322]

In 2023, Firefox was the fourth-most widely used desktop browser, and it was the fourth-most popular with 3.23% of worldwide usage share of web browsers across all platforms.

According to the Firefox Public Data report by Mozilla, the active monthly count of Desktop clients has decreased from around 310 million in 2017 to 200 million in 2023.^[324] From Oct 2020, the desktop market share of Firefox started to decline in countries where it used to be the most popular. In Eritrea, it dropped from 50% in Oct 2020 to 9.32% in Sept 2021. In Cuba, it dropped from 54.36% in Sept 2020 to 38.42% in Sept 2021.^[325][326]

The UK ^[327] and US ^[328] governments both follow the 2% rule. This states that only browsers with more than 2% market share among visitors of their websites will be supported. There are concerns that support for Firefox will be dropped because as of December 29th 2023, the browser market share among US government website visitors is 2.2%. ^[329]

Third-party forks

In addition to versions of Firefox made internally and the email client Mozilla Thunderbird,^[330] there are several third-party web browsers based on Firefox,^[331] including:

See also

• Firefox User Extension Library
• History of the web browser
• List of free and open-source software packages
• Mozilla Prism
• XULRunner

References

Further reading

External links

• Official website
• Firefox at Curlie
• Firefox at Microsoft Store