free and open-source
Free and open-source software (FOSS) is software available under a Software license, license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term ...
web browser
A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's scr ...
developed by the
Mozilla Foundation
The Mozilla Foundation is an American non-profit organization that exists to support and collectively lead the Open-source software, open source Mozilla project. Founded in July 2003, the organization sets the policies that govern development, ...
and its subsidiary, the
Mozilla Corporation
The Mozilla Corporation is a wholly owned subsidiary of the Mozilla Foundation that coordinates and integrates the development of Internet-related applications such as the Firefox web browser, by a global community of open-source developers, s ...
. It uses the
Gecko
Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates. They range from .
Geckos are unique among lizards ...
rendering engine to display web pages, which implements current and anticipated web standards. Firefox is available for
Windows 10
Windows 10 is a major release of Microsoft's Windows NT operating system. The successor to Windows 8.1, it was Software release cycle#Release to manufacturing (RTM), released to manufacturing on July 15, 2015, and later to retail on July 2 ...
or later versions of
Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
,
macOS
macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
, and
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
and
Unix-like
A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...
operating systems, including
FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...
,
OpenBSD
OpenBSD is a security-focused operating system, security-focused, free software, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking NetBSD ...
,
NetBSD
NetBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was fork (software development), forked. It continues to ...
, and other operating systems, such as
ReactOS
ReactOS is a Free and open-source software, free and open-source operating system for i586/amd64 personal computers that is intended to be binary-code compatibility, binary-compatible with computer programs and device drivers developed for Wind ...
iOS
Ios, Io or Nio (, ; ; locally Nios, Νιός) is a Greek island in the Cyclades group in the Aegean Sea. Ios is a hilly island with cliffs down to the sea on most sides. It is situated halfway between Naxos and Santorini. It is about long an ...
. However, as with all other iOS web browsers, the iOS version uses the
WebKit
WebKit is a browser engine primarily used in Apple's Safari web browser, as well as all web browsers on iOS and iPadOS. WebKit is also used by the PlayStation consoles starting with the PS3, the Tizen mobile operating systems, the Amazon K ...
layout engine instead of Gecko due to platform requirements. An optimized version is also available on the
Amazon Fire TV
Amazon Fire TV (formerly stylized as amazon fireTV) is a line of digital media players and microconsoles developed by Amazon since November 2014. The devices are small network appliances that deliver digital audio and video content streamed v ...
as one of the two main browsers available with Amazon's Silk Browser.
Firefox is the
spiritual successor
A spiritual successor (sometimes called a spiritual sequel) is a product or fictional work that is similar to, or directly inspired by, another previous product or work, but (unlike a traditional prequel or sequel) does not explicitly continue th ...
of
Netscape Navigator
The 1990s releases of the Netscape (web browser), Netscape line referred to as Netscape Navigator were a series of now discontinued web browsers. from versions 1 to 4.08. It was the Core product, flagship product of the Netscape, Netscape Comm ...
, as the
Mozilla
Mozilla is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops, publishes and supports Mozilla products, thereby promoting free software and open standards. The community is supported institution ...
community was created by
Netscape
Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California, and then Dulles, Virginia. Its Netscape web browser was o ...
in 1998, before its 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
The Mozilla Application Suite (originally known as Mozilla, marketed as the Mozilla Suite) is a discontinued cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition ...
bundle. During its
beta
Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...
phase, it proved to be popular with its testers and was praised for its speed, security, and add-ons compared to
Microsoft
Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
's then-dominant Internet Explorer 6. It was released on November 9, 2004, and challenged
Internet Explorer
Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated as IE or MSIE) is a deprecation, retired series of graphical user interface, graphical web browsers developed by Microsoft that were u ...
's dominance with 60 million downloads within nine months. In November 2017, Firefox began incorporating new technology under the code name "
Quantum
In physics, a quantum (: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a property can be "quantized" is referred to as "the hypothesis of quantization". This me ...
user interface
In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...
.
Firefox usage share grew to a peak of 32.21% in November 2009, with Firefox 3.5 overtaking
Internet Explorer 7
Windows Internet Explorer 7 (IE7) (codenamed Rincon) is a version of Internet Explorer, a web browser for Windows. It was released by Microsoft on October 18, 2006. It was the first major update to the browser since 2001. It does not support ve ...
, although not all versions of Internet Explorer as a whole; its usage then declined in competition with
Google Chrome
Google Chrome is a web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS, iOS, iPadOS, an ...
. , according to
StatCounter
StatCounter is a web traffic analysis website started in 1999. Access to basic services is free to use and advanced services can cost between and US$119 a month. StatCounter is based in Dublin, Ireland. The statistics from StatCounter are used ...
, it had a 6.36% usage share on traditional PCs (i.e. as a desktop browser), making it the fourth-most popular PC web browser after Google Chrome (65%),
Microsoft Edge
Microsoft Edge is a Proprietary Software, proprietary cross-platform software, cross-platform web browser created by Microsoft and based on the Chromium (web browser), Chromium open-source project, superseding Edge Legacy. In Windows 11, Edge ...
(14%), and
Safari
A safari (; originally ) is an overland journey to observe wildlife, wild animals, especially in East Africa. The so-called big five game, "Big Five" game animals of Africa – lion, African leopard, leopard, rhinoceros, African elephant, elep ...
Netscape
Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California, and then Dulles, Virginia. Its Netscape web browser was o ...
's sponsorship and developer-driven
feature creep
Feature creep is the excessive ongoing expansion or addition of new features in a product, especially in computer software, video games (where it should not be confused with power creep) and consumer and business electronics. These extra feature ...
compromised the utility of the Mozilla browser. To combat what they saw as the Mozilla Suite's
software bloat
Software bloat is a process whereby successive versions of a computer program become perceptibly slower, use more memory, disk space or processing power, or have higher hardware requirements than the previous version, while making only dubious ...
, they created a standalone browser, with which they intended to replace the Mozilla Suite. Version 0.1 was released on September 23, 2002. On April 3, 2003, the
Mozilla Organization
The Mozilla Foundation is an American non-profit organization that exists to support and collectively lead the open source Mozilla project. Founded in July 2003, the organization sets the policies that govern development, operates critical infr ...
announced that it planned to change its focus from the Mozilla Suite to Firefox and Thunderbird.
The Firefox project has undergone several name changes. 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
The 1990s releases of the Netscape (web browser), Netscape line referred to as Netscape Navigator were a series of now discontinued web browsers. from versions 1 to 4.08. It was the Core product, flagship product of the Netscape, Netscape Comm ...
, after it was sidelined by Microsoft Internet Explorer in the "
First Browser War
A browser war is a competition for dominance in the usage share of web browsers. The "first browser war" (1995–2001) occurred between proponents of Internet Explorer and Netscape Navigator, and the "second browser war" (2004–2017) between tho ...
"). Phoenix was renamed in 2003 due to a trademark claim from
Phoenix Technologies
Phoenix Technologies Ltd. is an American company that designs, develops and supports core system software for personal computers and other computing devices. The company's products commonly referred to as BIOS (Basic Input/Output System) or fir ...
. The replacement name, Firebird, provoked an intense response from the
Firebird
Firebird and fire bird may refer to:
Mythical birds
* Phoenix (mythology), sacred firebird found in the mythologies of many cultures
** Fenghuang, sometimes called Chinese phoenix
* Vermilion bird, one of the four symbols of the Chinese constella ...
database software project. 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. The name Firefox was said to be derived from a nickname of the
red panda
The red panda (''Ailurus fulgens''), also known as the lesser panda, is a small mammal native to the eastern Himalayas and southwestern China. It has dense reddish-brown fur with a black belly and legs, white-lined ears, a mostly white muzz ...
, which became the mascot for the newly named project. For the abbreviation of Firefox, Mozilla prefers ''Fx'' or ''fx,'' although it is often abbreviated as ''FF'' or Ff.
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
''Forbes'' () is an American business magazine founded by B. C. Forbes in 1917. It has been owned by the Hong Kong–based investment group Integrated Whale Media Investments since 2014. Its chairman and editor-in-chief is Steve Forbes. The co ...
'' and ''
The Wall Street Journal
''The Wall Street Journal'' (''WSJ''), also referred to simply as the ''Journal,'' is an American newspaper based in New York City. The newspaper provides extensive coverage of news, especially business and finance. It operates on a subscriptio ...
''. Among Firefox's popular features were the integrated pop-up blocker,
tabbed browsing
In interface design, a tab is a graphical user interface object that allows multiple documents or Panel (computer software), panels to be contained within a single window (computing), window, using tabs as a navigational widget for switching be ...
, 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
Opera is a form of History of theatre#European theatre, Western theatre in which music is a fundamental component and dramatic roles are taken by Singing, singers. Such a "work" (the literal translation of the Italian word "opera") is typically ...
, Firefox was the first of these browsers to have achieved large-scale adoption so quickly. Firefox attracted attention as an alternative to
Internet Explorer
Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated as IE or MSIE) is a deprecation, retired series of graphical user interface, graphical web browsers developed by Microsoft that were u ...
, 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
ActiveX is a deprecated software framework created by Microsoft that adapts its earlier Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content downloaded from a network, particularly from the World Wide W ...
component, and vulnerability to spyware and malware installation. Microsoft responded by releasing
Windows XP
Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct successor to Windows 2000 for high-end and business users a ...
Service Pack 2, which added several important security features to Internet Explorer 6.
Version 1.0 of Firefox was released on November 9, 2004. 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.
In 2016, Mozilla announced a project known as
Quantum
In physics, a quantum (: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a property can be "quantized" is referred to as "the hypothesis of quantization". This me ...
, 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
Google Chrome is a web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS, iOS, iPadOS, an ...
, 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. 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.
On May 3, 2019, the expiry of an intermediate signing certificate on Mozilla servers caused Firefox to automatically disable and lock all browser extensions (add-ons). Mozilla began the roll-out of a fix shortly thereafter, using their Mozilla Studies component.
Support for
Adobe Flash
Adobe Flash (formerly Macromedia Flash and FutureSplash) is a mostly discontinuedAlthough it is discontinued by Adobe Inc., for the Chinese market it is developed by Zhongcheng and for the international enterprise market it is developed by Ha ...
was dropped on January 6, 2021, with the release of Firefox 85.
On June 1, 2021, Firefox's 'Proton' redesign was offered through its stable release channel after being made available in the beta builds. While users were initially allowed to revert to the old design through about:config, the corresponding key-value pairs reportedly stopped working in later builds, resulting in criticism. These included accessibility concerns despite Mozilla's claim to "continue to work with the accessibility community" and had not been resolved .
On January 13, 2022, an issue with Firefox's HTTP/3 implementation resulted in a widespread outage for several hours.
On September 26, 2023, Firefox 118.0 introduced on-device translation of web page content.
On January 23, 2024, along with the release of Firefox 122.0, Mozilla introduced an official APT repository for
Debian
Debian () is a free and open-source software, free and open source Linux distribution, developed by the Debian Project, which was established by Ian Murdock in August 1993. Debian is one of the oldest operating systems based on the Linux kerne ...
-based
Linux distribution
A Linux distribution, often abbreviated as distro, is an operating system that includes the Linux kernel for its kernel functionality. Although the name does not imply product distribution per se, a distro—if distributed on its own—is oft ...
s.
Features
Features of the desktop edition include
tabbed browsing
In interface design, a tab is a graphical user interface object that allows multiple documents or Panel (computer software), panels to be contained within a single window (computing), window, using tabs as a navigational widget for switching be ...
drag and drop
In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user (computing), user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, i ...
, a
download manager
A download manager is a type of software that manages the downloading of files from the Internet, which may be built into a web browser, or as a standalone program.
Functions
A download manager manages files being downloaded from the internet. ...
,
user profile
A user profile is a collection of settings and information associated with a user. It contains critical information that is used to identify an individual, such as their name, age, portrait photograph and individual characteristics such as kn ...
management,
private browsing
Private browsing (also known as incognito mode or private mode) is a feature in most web browsers that enhances user privacy. In this mode, the browser initiates a temporary session separate from its main session and user data. The browsing ...
, bookmark tags, bookmark exporting, offline mode, a
screenshot
A screenshot (also known as screen capture or screen grab) is an analog or digital image that shows the contents of a computer display. A screenshot is created by a (film) camera shooting the screen or the operating system
An operating sys ...
tool,
web development tools
Web development tools (often abbreviated to dev tools) allow web developers to test, modify and debug their websites. They are different from website builders and integrated development environments (IDEs) in that they do not assist in the direct ...
, a "page info" feature which shows a list of page metadata and multimedia items, a configuration menu at about:config for
power user
A power user is a user of computers, software and other electronic devices who uses advanced features of computer hardware, operating systems, programs, or websites which are not used by the average user. A power user might not have extensive tech ...
s, and location-aware browsing (also known as "
geolocation
Geopositioning is the process of determining or estimating the geographic position of an object or a person.
Geopositioning yields a set of Geographic coordinate system, geographic coordinates (such as latitude and longitude) in a given map datum ...
") based on a Google service. (section "''What information is being sent, and to whom? (...)''") Firefox has an integrated search system which uses Google by default in most markets.DNS over HTTPS is another feature whose default behaviour is determined geographically.
Firefox provides an environment for web developers in which they can use built-in tools, such as the Error Console or the
DOM Inspector
DOM Inspector (DOMi) is a web developer tool created by Joe Hewitt and was originally included in Mozilla Application Suite as well as versions of Mozilla Firefox prior to Firefox 3. It is now included in Firefox, and SeaMonkey. Its main purp ...
, and
extensions
Extension, extend or extended may refer to:
Mathematics
Logic or set theory
* Axiom of extensionality
* Extensible cardinal
* Extension (model theory)
* Extension (proof theory)
* Extension (predicate logic), the set of tuples of values t ...
, such as Firebug and more recently there has been an integration feature with
Pocket
A pocket is a bag- or envelope-like receptacle either fastened to or inserted in an article of clothing to hold small items. Pockets are also attached to luggage, backpacks, and similar items. In older usage, a pocket was a separate small bag o ...
. Firefox Hello was an implementation of
WebRTC
WebRTC (Web Real-Time Communication) is a free and open-source project providing web browsers and mobile applications with real-time communication (RTC) via application programming interfaces (APIs). It allows audio and video communication and ...
, 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.
Former features include a
File Transfer Protocol
The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and d ...
(FTP) client for browsing file servers, the ability to block images from individual domains (until version 72), a 3D page inspector (versions 11 to 46), tab grouping (until version 44), and the ability to add customized extra toolbars (until version 28).
HTML
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...
JavaScript
JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior.
Web browsers have ...
, with
API
An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...
known as WebExtensions, which is designed to be compatible with
Google Chrome
Google Chrome is a web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS, iOS, iPadOS, an ...
and
Microsoft Edge
Microsoft Edge is a Proprietary Software, proprietary cross-platform software, cross-platform web browser created by Microsoft and based on the Chromium (web browser), Chromium open-source project, superseding Edge Legacy. In Windows 11, Edge ...
extension systems. Firefox previously supported add-ons using the XUL and
XPCOM
Cross Platform Component Object Model (XPCOM) is a cross-platform component model from Mozilla. It is similar to Component Object Model (COM), Common Object Request Broker Architecture (CORBA) and system object model (SOM). It features multiple ...
APIs, which allowed them to directly access and manipulate much of the browser's internal functionality. As compatibility was not included in the multi-process architecture, XUL add-ons have been deemed ''Legacy add-ons'' and are no longer supported on Firefox 57 "Quantum" and newer.
Mozilla has occasionally installed extensions for users without their permission. This happened in 2017 when an extension designed to promote the show ''
Mr. Robot
''Mr. Robot'' is an American drama thriller television series created by Sam Esmail for USA Network. It stars Rami Malek as Elliot Alderson, a cybersecurity engineer and hacker with social anxiety disorder, clinical depression, and dissoci ...
'' was silently added in an update to Firefox.
Themes
Firefox can have themes added to it, which users can create or download from third parties to change the appearance of the browser. Firefox also provides dark, light, and system themes.
Guest session
In 2013, Firefox for Android added a ''guest session'' mode, which wiped browsing data such as tabs, cookies, and history at the end of each guest session. Guest session data was kept even when restarting the browser or device, and deleted only upon a manual exit. The feature was removed in 2019, purportedly to "''streamline the experience''".
Standards
Firefox implements many
web standards
Web standards are the formal, non-proprietary standards and other technical specifications that define and describe aspects of the World Wide Web. In recent years, the term has been more frequently associated with the trend of endorsing a set of st ...
HTML5
HTML5 (Hypertext Markup Language 5) is a markup language used for structuring and presenting hypertext documents on the World Wide Web. It was the fifth and final major HTML version that is now a retired World Wide Web Consortium (W3C) recommend ...
),
XML
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...
,
XHTML
Extensible HyperText Markup Language (XHTML) is part of the family of XML markup languages which mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which Web pages are formulated.
While HTML, pr ...
,
MathML
Mathematical Markup Language (MathML) is a pair of mathematical markup languages, an application of XML for describing mathematical notations and capturing both its structure and content. Its aim is to natively integrate mathematical formulae ...
JavaScript
JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior.
Web browsers have ...
XSLT
XSLT (Extensible Stylesheet Language Transformations) is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text, or XSL Formatting Objects. These formats c ...
,
XPath
XPath (XML Path Language) is an expression language designed to support the query or transformation of XML documents. It was defined by the World Wide Web Consortium (W3C) in 1999, and can be used to compute values (e.g., strings, numbers, or ...
, and APNG (Animated PNG) images with alpha transparency. Firefox also implements standards proposals created by the
WHATWG
The Web Hypertext Application Technology Working Group (WHATWG) is a community of people interested in evolving HTML and related technologies. The WHATWG was founded by individuals from Apple Inc., the Mozilla Foundation and Opera Software, ...
such as client-side storage, and the
canvas element
The HTML canvas element allows for dynamic, scriptable rendering of 2D shapes and bitmap images. Introduced in HTML5, it is a low level, procedural model that updates a bitmap. The element also helps in making 2D games.
While the element ...
. These standards are implemented through the Gecko layout engine, and
SpiderMonkey
SpiderMonkey is an open-source JavaScript and WebAssembly engine by the Mozilla Foundation. The engine powers the Firefox Web browser and has used multiple generations of JavaScript just-in-time (JIT) compilers, including TraceMonkey, Jäg ...
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. 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. Because the SVG font tests were removed from the Acid3 test in September 2011, Firefox 4 and greater scored 100/100.
Firefox also implements "Safe Browsing," a
proprietary protocol
In telecommunications, a proprietary protocol is a communications protocol owned by a single organization or individual.
Intellectual property rights and enforcement
Ownership by a single organization gives the owner the ability to place restricti ...
from Google used to exchange data related with phishing and malware protection.
Firefox supports the playback of video content protected by
HTML5
HTML5 (Hypertext Markup Language 5) is a markup language used for structuring and presenting hypertext documents on the World Wide Web. It was the fifth and final major HTML version that is now a retired World Wide Web Consortium (W3C) recommend ...
Encrypted Media Extensions
Encrypted Media Extensions (EME) is a W3C specification for providing a communication channel between web browsers and the Content Decryption Module (CDM) software which implements digital rights management (DRM). This allows the use of HTML vide ...
(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
{{Short pages monitor
As a workaround for the issue, a preloader application was created that loaded components of Firefox on startup, similar to Internet Explorer. A
Windows Vista
Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, released five years earlier, which was then the longest time span between successive releases of Microsoft W ...
feature called SuperFetch performs a similar task of preloading Firefox if it is used often enough.
Tests performed by ''
PC World
''PC World'' (stylized as PCWorld) is a global computer magazine published monthly by IDG. Since 2013, it has been an online-only publication.
It offers advice on various aspects of PCs and related items, the Internet, and other personal tec ...
'' and Zimbra in 2006 indicated that Firefox 2 used less memory than Internet Explorer 7. Firefox 3 used less memory than Internet Explorer 7, Opera 9.50 Beta,
Safari
A safari (; originally ) is an overland journey to observe wildlife, wild animals, especially in East Africa. The so-called big five game, "Big Five" game animals of Africa – lion, African leopard, leopard, rhinoceros, African elephant, elep ...
3.1 Beta, and Firefox 2 in tests performed by Mozilla, CyberNet, and The Browser World. In mid-2009, BetaNews benchmarked Firefox 3.5 and declared that it performed "nearly ten times better on XP than Microsoft Internet Explorer 7".
2010s
In January 2010, Lifehacker compared the performance of Firefox 3.5, Firefox 3.6, Google Chrome 4 (stable and Dev versions), Safari 4, and Opera (10.1 stable and 10.5 pre-alpha versions). Lifehacker timed how long browsers took to start and reach a page (both right after boot-up and after running at least once already), timed how long browsers took to load nine tabs at once, tested JavaScript speeds using Mozilla's Dromaeo online suite (which implements Apple's
SunSpider
A browser speed test is a computer benchmark that scores the performance of a web browser, by measuring the browser's efficiency in completing a predefined list of tasks. In general the testing software is available online, located on a website, w ...
and Google's V8 tests) and measured memory usage using Windows 7's process manager. They concluded that Firefox 3.5 and 3.6 were the fifth- and sixth-fastest browsers, respectively, on startup, 3.5 was third- and 3.6 was sixth-fastest to load nine tabs at once, 3.5 was sixth- and 3.6 was fifth-fastest on the JavaScript tests. They also concluded that Firefox 3.6 was the most efficient with memory usage followed by Firefox 3.5.
In February 2012, ''
Tom's Hardware
''Tom's Hardware'' is an online publication owned by Future plc and focused on technology. It was founded in 1996 by Thomas Pabst. It provides articles, news, price comparisons, videos and reviews on computer hardware and high technology. The s ...
'' performance tested Chrome 17, Firefox 10, Internet Explorer 9, Opera 11.61, and Safari 5.1.2 on Windows 7. ''Tom's Hardware'' summarized their tests into four categories: Performance, Efficiency, Reliability, and Conformance. In the performance category they tested
HTML5
HTML5 (Hypertext Markup Language 5) is a markup language used for structuring and presenting hypertext documents on the World Wide Web. It was the fifth and final major HTML version that is now a retired World Wide Web Consortium (W3C) recommend ...
,
Java
Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...
,
JavaScript
JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior.
Web browsers have ...
Silverlight
Microsoft Silverlight is a discontinued application framework designed for writing and running rich internet applications, similar to Adobe's runtime, Adobe Flash. While early versions of Silverlight focused on streaming media, later version ...
, and
WebGL
WebGL (short for Web Graphics Library) is a JavaScript Application programming interface, API for rendering interactive 2D and 3D graphics within any compatible web browser without the use of plug-in (computing), plug-ins. WebGL is fully integra ...
( WebGL 2 is current as of version 51; and Java and Silverlight stop working as of version 52)—they also tested startup time and page load time. The performance tests showed that Firefox was either "acceptable" or "strong" in most categories, winning three categories (HTML5, HTML5
hardware acceleration
Hardware acceleration is the use of computer hardware designed to perform specific functions more efficiently when compared to software running on a general-purpose central processing unit (CPU). Any transformation of data that can be calcula ...
, and Java) only finishing "weak" in CSS performance. In the efficiency tests, ''Tom's Hardware'' tested memory usage and management. With this category, it determined that Firefox was only "acceptable" at performing light memory usage, while it was "strong" at performing heavy memory usage. In the reliability category, Firefox performed a "strong" amount of proper page loads. For the final category, conformance, it was determined that Firefox had "strong" conformance for JavaScript and HTML5. So in conclusion, ''Tom's Hardware'' determined that Firefox was the best browser for Windows 7 OS, but that it only narrowly beat Google Chrome.
In June 2013, ''Tom's Hardware'' again performance tested Firefox 22, Chrome 27, Opera 12, and
Internet Explorer 10
Internet Explorer 10 (IE10) is the tenth version of the Internet Explorer web browser and the successor to Internet Explorer 9, released by Microsoft on September 4, 2012. It is the default browser on Windows 8 and Windows Server 2012, and wa ...
. They found that Firefox slightly edged out the other browsers in their "performance" index, which examined wait times, JavaScript execution speed, HTML5/CSS3 rendering, and hardware acceleration performance. Firefox also scored the highest on the "non-performance" index, which measured memory efficiency, reliability, security, and standards conformance, finishing ahead of Chrome, the runner-up. ''Tom's Hardware'' concluded by declaring Firefox the "sound" winner of the performance benchmarks.
In January 2014, a benchmark testing the memory usage of Firefox 29, Google Chrome 34, and
Internet Explorer 11
Internet Explorer 11 (IE11) is the eleventh and final version of the Internet Explorer web browser, by now retired. It was initially included in the release of Windows 8.1, Windows RT, Windows RT 8.1 and Windows Server 2012 R2 on October 17, 2013 ...
indicated that Firefox used the least memory when a substantial number of tabs were open.
In benchmark testing in early 2015 on a "high-end" Windows machine, comparing Microsoft Edge ">egacy Internet Explorer, Firefox, Chrome, and Opera, Firefox achieved the highest score on three of the seven tests. Four different JavaScript performance tests gave conflicting results. Firefox surpassed all other browsers on the Peacekeeper benchmark, but was behind the Microsoft products when tested with SunSpider. Measured with Mozilla's Kraken, it came second place to Chrome, while on Google's
Octane
Octane is a hydrocarbon and also an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers ...
challenge it took third behind Chrome and Opera. Firefox took the lead with WebXPRT, which runs several typical HTML5 and JavaScript tasks. Firefox, Chrome, and Opera all achieved the highest possible score on the Oort Online test, measuring WebGL rendering speed (WebGL 2 is now current). In terms of HTML5 compatibility testing, Firefox was ranked in the middle of the group.
A similar set of benchmark tests in 2016 showed Firefox's JavaScript performance on Kraken and the newer
Jetstream
Jet streams are fast flowing, narrow air currents in the Earth's atmosphere.
The main jet streams are located near the altitude of the tropopause and are westerly winds, flowing west to east around the globe. The northern hemisphere and th ...
tests trailing slightly behind all other tested browsers except Internet Explorer (IE), which performed relatively poorly. On Octane, Firefox came ahead of IE and Safari, but again slightly behind the rest, including
Vivaldi
Antonio Lucio Vivaldi (4 March 1678 – 28 July 1741) was an Italian composer, virtuoso violinist, impresario of Baroque music and Roman Catholic priest. Regarded as one of the greatest Baroque composers, Vivaldi's influence during his lif ...
and Microsoft Edge egacy Edge egacytook overall first place on the Jetstream and Octane benchmarks.
2020s
In 2023 Microsoft published that it corrected a mistake in MS Windows after 5 years that slowed down especially Firefox.
Firefox Quantum
As of the adoption of Firefox 57 and Mozilla's Quantum project entering production browsers in November 2017, Firefox was tested to be faster than Chrome in independent JavaScript tests, and demonstrated to use less memory with many browser tabs opened. ''
TechRadar
''TechRadar'' is an online technology publication owned by Future plc. It has editorial teams in the United States, United Kingdom, and Australia that provide news and reviews of tech products and gadgets. It was launched in 2008 and expanded t ...
'' rated it as the fastest web browser in a May 2019 report.
Usage share
Downloads have continued at an increasing rate since Firefox 1.0 was released, and Firefox had already been downloaded over one billion times. This number does not include downloads using software updates or those from third-party websites. 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
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
asked all employees (about 400,000) to use Firefox as their default browser.
Firefox was the second-most used web browser until November 2011, when Google Chrome surpassed it. According to Mozilla, Firefox had more than 450 million users .
In October 2024, Firefox was the fourth-most widely used desktop browser, and it was the fourth-most popular with 2.95% of worldwide
usage share of web browsers
The usage share of web browsers is the portion, often expressed as a percentage, of visitors to a group of web sites that use a particular web browser.
Accuracy
Measuring browser usage in the number of requests (page hits) made by each user a ...
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.
From October 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 October 2020 to 9.32% in September 2021.
In Cuba, it dropped from 54.36% in Sept 2020 to 38.42% in September 2021.
The UK and US 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 29, 2023, the browser market share among US government website visitors is 2.2%.
List of free and open-source software packages
This is a list of free and open-source software (FOSS) packages, computer software licensed under free software licenses and open-source licenses. Software that fits the Free Software Definition may be more appropriately called free software; ...
XULRunner
XULRunner is a discontinued, packaged version of the Mozilla platform to enable standalone desktop application development using XUL, developed by Mozilla. It replaced the ''Gecko Runtime Environment'', a stalled project with a similar purpose. ...
Microsoft Store
The Microsoft Store (formerly known as the Windows Store) is a digital distribution platform operated by Microsoft. It was created as an app store for Windows 8 as the primary means of distributing Universal Windows Platform apps. With ...