History of Firefox

Contents
History of Firefox v1 • v1.5 v2 v3 • v3.5 • v3.6 v4 v5 and later Features of Firefox Gecko Add-ons Extensions Firefox market adoption
Origins and lineage
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Category

The Mozilla Firefox project was created by Dave Hyatt and Blake Ross as an experimental branch of the Mozilla browser.

Firefox 1.0 was released on November 9, 2004, Firefox 1.5 was released on November 29, 2005, and version 2.0 was released on October 24, 2006. Firefox 3.0 was released on June 17, 2008, with version 3.5 and version 3.6 released on June 30, 2009 and January 21, 2010, respectively. Version 4.0 was released on March 22, 2011. Since the version 5.0, a rapid release cycle was put into effect, resulting in a new major version release every six weeks on Tuesday.

The latest version, Firefox 50.0, was released on November 15, 2016.

Naming

The project that became Firefox started as an experimental branch of the Mozilla Suite called m/b (or mozilla/browser). After it had been sufficiently developed, binaries for public testing appeared in September 2002 under the name Phoenix. This name carried the implication of the mythical firebird that rose triumphantly from the ashes of its dead predecessor, in this case from the "ashes" of Netscape Navigator after it had been killed off by Microsoft's Internet Explorer in the "First browser war". The history of the name Mozilla goes all the way back to the internal codename for the original 1994 Netscape Navigator browser, with the name meaning "Mosaic killer" and aiming to some similarity with the building-crushing Godzilla, as the company's goal was to displace NCSA Mosaic as the world's number one web browser.^[1] The name Mozilla was revived as the 1998 open sourcing spinoff organization from Netscape.

The Phoenix name was kept until April 14, 2003, when it was changed because of a trademark dispute with the BIOS manufacturer, Phoenix Technologies (which produces a BIOS-based browser called Phoenix FirstWare Connect). The new name, Firebird, met with mixed reactions, particularly as the Firebird database server already carried the name. In response, the Mozilla Foundation stated that the browser should always bear the name Mozilla Firebird to avoid confusion with the database software. Continuing pressure from the Firebird community forced another change,^[2] and on February 9, 2004 the project was renamed Mozilla Firefox (or Firefox for short).^[3]

The name "Firefox" (a reference to the red panda)^[4] was chosen for its similarity to "Firebird", but also for its uniqueness in the computing industry. To ensure that no further name changes would be necessary, the Mozilla Foundation began the process of registering Firefox^[5] as a trademark with the United States Patent and Trademark Office in December 2003. This trademark process led to a delay of several months in the release of Firefox 0.8 when the foundation discovered that Firefox had already been registered as a trademark in the UK^[6] for Charlton Company software.^[7] The situation was resolved when the foundation was given a license to use Charlton's European trademark.

Early versions

Hyatt, Ross, Hewitt and Chanial^[8] developed their browser to combat the perceived software bloat of the Mozilla Suite (codenamed, internally referred to, and continued by the community as SeaMonkey), which integrated features such as IRC, mail and news, and WYSIWYG HTML editing into one internet suite.

Firefox retains the cross-platform nature of the original Mozilla browser, using the XUL user interface markup language. The use of XUL makes it possible to extend the browser's capabilities through the use of extensions and themes. The development and installation processes of these add-ons raised security concerns, and with the release of Firefox 0.9, the Mozilla Foundation opened a Mozilla Update website containing "approved" themes and extensions. The use of XUL sets Firefox apart from other browsers, including other projects based on Mozilla's Gecko layout engine and most other browsers, which use interfaces native to their respective platforms (Galeon and Epiphany use GTK+; K-Meleon uses MFC; and Camino uses Cocoa). Many of these projects started before Firefox, and probably served as inspiration.

On February 5, 2004 AMS, a business and IT consulting company, categorized Mozilla Firefox (then known as Firebird) as a "Tier 1" ("Best of Breed") open-source product, considering it technically strong and virtually risk-free.^[9]

Version 1.0

Firefox 1.0 was released on November 9, 2004.^[10] The launch of version 1.0 was accompanied by "a respectable amount of pre-launch fervor"^[11] including a fan-organized campaign to run a full-page ad in The New York Times.

Although the Mozilla Foundation had intended to make the Mozilla Suite obsolete and replace it with Firefox, the Foundation continued to maintain the suite until April 12, 2006^[12] because it had many corporate users and was bundled with other software. The Mozilla community (as opposed to the Foundation) continues to release new versions of the suite, using the product name SeaMonkey to avoid confusion with the original Mozilla Suite.

Version 1.5

On June 23, 2005, the Mozilla Foundation announced that Firefox 1.1, which later become 1.5, and other new Mozilla products would no longer support Mac OS X v10.1, in order to improve the quality of Firefox releases on Mac OS X v10.2 and above.

Firefox 1.5 was released on November 30, 2005. While Firefox 1.5 was originally slated to arrive later, the Mozilla Foundation abandoned the 1.1 release plan after the first two 1.1 alpha builds, merging it with the feature set of 1.5, which ended up being released later than the original 1.1 date. The new version resynchronized the code base of the release builds (as opposed to nightly builds) with the core "trunk", which contained additional features not available in 1.0, as it branched from the trunk around the 0.9 release. As such, there was a backlog of bug fixes between 0.9 and the release of 1.0, which were made available in 1.5. Version 1.5 implemented a new Mac-like options interface, the subject of much criticism from Microsoft Windows and Linux users, with a "Sanitize" action to allow someone to clear their privacy-related information without manually clicking the "Clear All" button. In Firefox 1.5, a user could clear all privacy-related settings simply by exiting the browser or using a keyboard shortcut, depending on their settings. Moreover, the software update system was improved (with binary patches now possible). There were also improvements in the extension management system, with a number of new developer features.

In addition, Firefox 1.5 had preliminary SVG 1.1 support.^[13]

Alpha builds of Firefox 1.5 (1.1a1 and 1.1a2) did not carry Firefox branding; they were labeled "Deer Park" (which was Firefox 1.5's internal codename) and contained a different program icon. This was done to dissuade end-users from downloading preview versions, which are intended for developers only.

Firefox 1.5.0.12 was the final version supported on Windows 95.

Version 2

On October 24, 2006, Mozilla released Firefox 2. This version includes updates to the tabbed browsing environment; the extensions manager; the GUI (Graphical User Interface); and the find, search and software update engines; a new session restore feature; inline spell checking; and an anti-phishing feature which was implemented by Google as an extension,^[14][15] and later merged into the program itself.^[16] In December 2007, Firefox Live Chat was launched. It allows users to ask volunteers questions through a system powered by Jive Software, with guaranteed hours of operation and the possibility of help after hours.^[17] Firefox 2.0.0.20 is the final version which can run under an unmodified installation of Windows NT 4.0, Windows 98, and Windows ME.^[18]

Mozilla Firefox 2.0.0.x was the final version supported on Windows NT 4.0, 98 and Me. Mozilla Corporation announced it would not develop new versions of Firefox 2 after the 2.0.0.20 release, but continued Firefox 2 development as long as other programs, such as Thunderbird mail client, depended on it. The final internal release was 2.0.0.22, released in late April 2009.

Version 3

Firefox 3 was released on June 17, 2008,^[19] by the Mozilla Corporation. Firefox 3 uses version 1.9 of the Mozilla Gecko layout engine for displaying web pages. This version fixes many bugs, improves standard compliance, and implements new web APIs.^[20] Other new features include a redesigned download manager, a new "Places" system for storing bookmarks and history, and separate themes for different operating systems. Tabbed browsing was more popularised in this version. The final version under 3.0 is Firefox 3.0.19.

Development stretches back to the first Firefox 3 beta (under the codename 'Gran Paradiso'^[21]) which had been released several months earlier on November 19, 2007,^[22] and was followed by several more beta releases in spring 2008 culminating in the June release.^[23] Firefox 3 had more than 8 million unique downloads the day it was released, setting a Guinness World Record.^[24]

Version 3.5

Version 3.5, codenamed Shiretoko,^[25] adds a variety of new features to Firefox. Initially numbered Firefox 3.1, Mozilla developers decided to change the numbering of the release to 3.5, in order to reflect a significantly greater scope of changes than originally planned.^[26] The final release was on June 30, 2009. The changes included much faster performance thanks to an upgrade to SpiderMonkey JavaScript engine called TraceMonkey and rendering improvements,^[27] and support for the <video> and <audio> tags as defined in the HTML5 specification, with a goal to offer video playback without being encumbered by patent problems associated with many video technologies.^[28] Cross-site XMLHttpRequests (XHR), which can allow for more powerful web applications and an easier way to implement mashups, are also implemented in 3.5.^[29] A new global JSON object contains native functions to efficiently and safely serialize and deserialize JSON objects, as specified by the ECMAScript 3.1 draft.^[30] Full CSS 3 selector support has been added. Firefox 3.5 uses the Gecko 1.9.1 engine, which includes a few features that were not included in the 3.0 release. Multi-touch trackpad support was also added to the release, including gesture support like pinching for zooming and swiping for back and forward.^[31] Firefox 3.5 also features an updated logo.^[32]

Version 3.6

Version 3.6, released on January 21, 2010, uses the Gecko 1.9.2 engine and includes several interface improvements, such as "personas". This release was referred to as 3.2 before 3.1 was changed to 3.5. The codename for this version was Namoroka. This is the last major, official version to run on PowerPC-based Macintoshes.

One minor update to Firefox 3.6, version 3.6.4 (code-named Lorentz) is the first minor update to make non-intrusive changes other than minor stability and security fixes.^[33] It adds Out of Process Plugins (OOPP), which runs plugins in a separate process, allowing Firefox to recover from plugin crashes.

Firefox 3.6.6 lengthens the amount of time a plug-in is allowed to be unresponsive before the plug-in quits.^[34]

Support for Firefox 3.6 ended on April 24, 2012.^[35]

Version 4.0

Firefox 3.7 (Gecko 1.9.3) Alpha 1 was released on February 10, 2010.^[36][37] Alpha 2 was released on March 1, 2010, Alpha 3 on March 17, Alpha 4 on April 12, and Alpha 5 on June 16.

The version number was changed to 4.0 (and Gecko's was changed to 2.0) starting with Beta 1, released on July 6, 2010.

Beta 2 was released on July 27, Beta 3 on August 11, Beta 4 on August 24, Beta 5 on September 7, Beta 6 (a chemspill release) on September 14.

After major delays, Beta 7 was finally released on November 10. Beta 7 was followed by Beta 8, released on December 21. Beta 9 was released on January 14, 2011, Beta 10 on January 25, Beta 11 on February 8, and Beta 12 on February 12.

Firefox then moved into the RC stage.^[38] The final version of Firefox 4 was released on March 22, 2011.^[39]

Version 4 brought a new user interface and is said to be faster.^[40] Early mockups of the new interface on Windows, Mac OS X, and Linux were first made available in July 2009.^[41][42][43] Other new features included improved notifications, tab groups, application tabs, a redesigned add-on manager, integration with Firefox Sync, and support for multitouch displays.^{[44][45][46][47][48]}

On October 13, 2006, Brendan Eich, Mozilla's Chief Technology Officer, wrote about the plans for "Mozilla 2", referring to the most comprehensive iteration (since its creation) of the overall platform on which Firefox and other Mozilla products run.^[49] Most of the objectives were gradually incorporated into Firefox through versions 3.0, 3.5, and 3.6. The largest changes, however, were planned for Firefox 4.

Firefox 4 was based on the Gecko 2.0 engine, which added or improved support for HTML5, CSS3, WebM, and WebGL.^[50][51] It also included a new JavaScript engine (JägerMonkey) and better XPCOM APIs.^[52]

Rapid release

Market Share Overview According to StatCounter data November 2016[53]

Browser % of Fx % of Total Old version, no longer supported: Firefox 2 0.14% 0.01% Old version, no longer supported: Firefox 3.x 1.28% 0.09% Old version, no longer supported: Firefox 4 — — Old version, no longer supported: Firefox 5–9 0.14% 0.01% Old version, no longer supported: Firefox 10–16 0.57% 0.04% Old version, no longer supported: Firefox 17–23 0.71% 0.05% Old version, no longer supported: Firefox 24–30 1.28% 0.09% Old version, no longer supported: Firefox 31–37 2.28% 0.16% Old version, no longer supported: Firefox 38–44 7.40% 0.52% Older version, yet still supported: Firefox 45 Firefox ESR 45 2.28% 0.16% Old version, no longer supported: Firefox 46 1.85% 0.13% Old version, no longer supported: Firefox 47 5.26% 0.37% Old version, no longer supported: Firefox 48 3.84% 0.27% Old version, no longer supported: Firefox 49 44.38% 3.12% Current stable version: Firefox 50 25.89% 1.82% Future release: Firefox 51 0.85% 0.06% All variants[54] 100% 7.03%

In April 2011, the development process was split into several "channels", each working on a build in a different stage of development. The most recent available build is called "Nightly Builds" and offers the latest, untested features and updates. The "Aurora" build is up to six weeks behind "Nightly" and offers functionality that has undergone basic testing. As of version 35, the "Aurora" channel has been renamed to the "Developer Edition" channel.^[55][56] The "Beta" channel is another six weeks away. It provides improved stability over the nightly builds and is the first development milestone that has the "Firefox" logo. "Release" is the current official version of Firefox.

New releases are planned to occur at six-week intervals.^[57] The stated aim of this faster-paced process is to get new features to users faster.^[58] This accelerated release cycle was met with criticism by users, as it often broke addon compatibility,^[59] as well as those who believe Firefox was simply trying to increase its version number to compare with other browsers such as Google Chrome.^[60]

Version 5

Firefox 5 was released on June 21, 2011,^[61] three months after the major release of Firefox 4. Firefox 5 is the first release in Mozilla's new rapid release plan, matching Google Chrome's rapid release schedule and rapid version number increments.^[62] Version 5 significantly improved the speed of web-related tasks, such as loading pages with combo boxes or MathML. Mozilla also integrated the HTML5 video WebM standard into the browser, allowing playback of WebM video.^[63]

Version 6

Mozilla released its Mozilla Firefox 6.0 on August 16, 2011. The update brought: permissions manager, new address bar highlighting (the domain name is black while the rest of the URL is gray^[64]), streamlining the look of the site identity block, quicker startup time, a ScratchPad JavaScript compiler, and many other new features. This update also brought the infamous feature that JavaScript entered in the address bar does not run.^[65]

Version 7

Firefox 7, released September 27, 2011, uses as much as 50% less memory than Firefox 4 as a result of the MemShrink project to reduce Firefox memory usage.^[66][67][68] Mozilla Firefox 7.0.1 was released a few days later, fixing a rare, but serious, issue with add-ons not being detected by the browser.^[69] The "http://" protocol indicator no longer appears in the URL.^[64]

Version 8

Firefox 8 was released on November 8, 2011. Firefox 8 verified that users really wanted any previously installed add-ons. Upon installation, a dialog box prompted users to enable or disable the add-ons. Add-ons installed by third-party programs were disabled by default, but user-installed add-ons were enabled by default. Mozilla judged that third-party-installed add-ons were problematic, taking away user control, lagging behind on compatibility and security updates, slowing down Firefox startup and page loading time, and cluttering the interface with unused toolbars.^[70]

Version 9

Firefox 9 was released on December 20, 2011; version 9.0.1 was released a day later. Firefox 9 includes various new features such as Type Inference, which boosts JavaScript performance up to 30%, improved theme integration for Mac OS X Lion, added two finger swipe navigation for Mac OS X Lion, added support for querying Do Not Track status via JavaScript, added support for font-stretch, improved support for text-overflow, improved standards support for HTML5, MathML, and CSS, and fixed several security problems. It also features a large list of bug fixes.^[71]

Version 10 (ESR)

Firefox 10 and Firefox ESR 10 were released on January 31, 2012. It is the first official extended support release. Firefox 10 hides the forward arrow button until there is a website to go forward to, or it is manually activated.^[72] Firefox 10 adds a Full Screen API and improved WebGL performance.^[73]

Firefox 10 assumed all add-ons were compatible with version 10, as long as they are written for at least Firefox 4. The add-on developer is able to alert Mozilla that the add-on is incompatible, overriding compatibility with version 10 or later. This new rule also does not apply to themes.^[74]

Firefox 10 added the CSS Style Inspector to the Page Inspector, which allow users to check out a site's structure and edit the CSS without leaving the browser.^[75]

Firefox 10 added support for CSS 3D Transforms and for anti-aliasing in the WebGL standard for hardware-accelerated 3D graphics. These updates mean that complex site and Web app animations will render more smoothly in Firefox, and that developers can animate 2D objects into 3D without plug-ins.^[73]

Version 11

Firefox 11 was released on March 13, 2012. Firefox 11 introduced many new features, including migration of bookmarks and history from Google Chrome,^[76] SPDY integrated services, Page Inspector Tilt (3D View), Add-on Sync, redesigned HTML5 video controls, and the Style Editor (CSS).^[77] The update also fixed many bugs, and improved developer tools.^[78]

Version 12

Firefox 12 was released on April 24, 2012. Firefox 12 introduced few new features, but it made many changes and laid the ground work for future releases. Firefox 12 for Windows added the Mozilla Maintenance Service which can update Firefox to a newer version without UAC prompt.^[79] It also added line numbers in the "Page Source" and centered find in page results. There were 89 improvements to Web Console, Scratchpad, Style Editor, Page Inspector, Style Inspector, HTML view and Page Inspector 3D view (Tilt).^[80] Many bugs were fixed, as well as many other minor under-the-hood changes.^[81][82] Firefox 12 is the final release to support Windows 2000 and Windows XP RTM & SP1.^[83][84]

Version 13

Firefox 13 was released on June 5, 2012.^[57] Firefox 13 adds and updates several features, such as an updated new tab^[85] and home tab page.^[86] The updated new tab page is a feature similar to the Speed Dial already present in Opera, Google Chrome, Apple Safari, and Internet Explorer. The new tab page will display nine of the user's most visited websites, along with a cached image.

In addition to the updated new tab and home tab page, Mozilla has added a user profile cleaner/reset, reduced hang times, and implemented tabs on demand.^[87] The user profile cleaner/reset provides a way for users to fix Firefox errors and glitches that may occur.^[88] Mozilla's tabs on demand restores tabs that were open in the previous session, but will keep the tabs unloaded until the user requests to view the page.^[89]

Starting with this version, Windows support was exclusively for Windows XP SP2/SP3, Windows Vista, & Windows 7.

Version 14

Firefox 14.0 for Android was released on June 26, 2012, just outside the regular release schedule of the web browser.^[57][90] In order to sync the version numbers of the desktop and mobile version of Firefox, Mozilla decided to release Firefox 14.0.1 for mobile and desktop on July 17, 2012, instead of Firefox 14.0 for the desktop and Firefox 14.0.1 for mobile clients.^[90]

A new hang detector (similar to how Mozilla currently collects other data) allows Mozilla to collect, analyze, and identify the cause of the browser freezing/hanging. Mozilla will use this information to improve the responsiveness of Firefox for future releases.^[91]

In addition to tackling freezing and not-responding errors that occur because of Firefox, Mozilla implemented opt-in activation for plugins such as Flash and Java. Mozilla wants to reduce potential problems that could arise through the unwanted use of third-party applications (malware, freezing, etc.).^[92]

URL complete will suggest the website that Firefox believes the user plans on visiting. It does this by inserting the remaining characters into the URL form box.^[93]

Firefox 14 has an optional GStreamer back-end for HTML5 video tag playback.^[94] This allows playback of H.264 if the codec is installed as a GStreamer plugin. GStreamer support is not enabled in the official builds, but can be enabled at compile time.

The first beta version of Firefox 14 was not beta 1, but beta 6^[95] and was released on June 5, 2012.

Version 15

Firefox 15 was released on August 28, 2012.^[57]

This version includes a "Responsive Design View" developer tool,^[96] adds support for the Opus audio format^[97] and adds preliminary native PDF support (turned off by default).^[98]

Silent updates automatically update Firefox to the latest version without notifying the user,^[99] a feature that the web browsers Google Chrome and Internet Explorer 8 and above have already implemented,^[100][101] although the user is able to disable that function.^[102]

Mozilla improved regular startup time for Windows users.^[103]

Version 16

Firefox 16 was released on October 9, 2012.

Plans for this version called for fixing of bugs still outstanding involving support of new features in Mac OS X Lion, improvements to startup speed when a user wants to restore a previous session,^[104] and support for viewing PDF files inline without a plugin.

Opus audio format is now enabled by default. Support for web apps was added.^[105]

The roll-out of Firefox 16.0.0 was stopped on October 10, 2012, after Mozilla detected a security flaw and recommended downgrading to 15.0.1 until the issue^[106] could be fixed. The security flaw was fixed in version 16.0.1, which was released the following day, October 11, 2012.^[107] Version 16.0.2 was released October 26, 2012. It fixed additional security issues, and is also the final release to support Mac OS X Leopard.^[108]

Version 17 (ESR)

Firefox 17 and Firefox ESR 17 were released on November 20, 2012.^[57] Firefox 17.0.1, with several bug fixes, launched on November 30, 2012.

Firefox 17 was not planned to bring as many user-facing features as previous releases; it brings improved display of location bar results,^[109] improvements to the silent update mechanism for users with incompatible add-ons,^[110] and refinements to the Click-To-Play system introduced in Firefox 14.^[111] A new feature for developers, an HTML tree editor^[112] is also included. Firefox 17 is the first version of the browser that uses SpiderMonkey 17.^[113]

Starting with this version, Mac OS X support is exclusively for Snow Leopard, Lion, and Mountain Lion.

Version 18

Firefox 18 was released on January 8, 2013.^[114] A new feature for Firefox 18 is IonMonkey, Mozilla's next generation JavaScript engine;^[115] it also uses some functions of WebRTC.^[116]

Firefox 18.0.1 was released on January 18, 2013, and added several bug fixes.^[117] Firefox 18.0.2 was released on February 5, 2013.

Version 19

Firefox 19 was released on February 19, 2013. Firefox 19 features a built-in PDF viewer.^[118] Firefox 19.0.1 was released on February 27, 2013 to fix stability issues for some AMD Radeon HD graphics cards in Windows 8.^[119] Firefox 19.0.2 was released on March 7, 2013 to address a security vulnerability in the HTML editor.^[120]

Version 20

Firefox 20 was released on April 2, 2013. A new feature of Firefox 20 is a panel-based download manager,^[121][122] along with H.264 decoding on the <video> tag (on Windows only), and per-window private browsing (per-tab private browsing on Android). It also includes a new developer toolbox, that combines all developer tools into one panel.

Firefox 20.0.1 was released on April 11, 2013, and included a Windows-only update to handle issues around handling UNC paths.^[123]

Version 21

Firefox 21 was released on May 14, 2013. The Social API now supports multiple providers, enhanced three-state UI for Do Not Track (DNT).

Version 22

Firefox 22 was released on June 25, 2013. WebRTC is now enabled by default.^[124] Partial CSS Flexbox support added (flex-wrap support is currently scheduled for Firefox 28^[125]). A new feature for Firefox 22 was OdinMonkey, Mozilla's next generation JavaScript engine.

Version 23

Firefox 23 was released on August 6, 2013. It includes an updated Firefox logo, mixed content blocking enabled by default to defend against man-in-the-middle attacks, implementation of the <input type="range"> form control attribute in HTML5, dropping support for the <blink> HTML element as well as text-decoration:blink CSS element, the restriction to have to "switch to a different search provider across the entire browser", and a global browser console, a new network monitor among other things. JavaScript is automatically enabled by the update, without regard to the previous setting, and the ability to turn it off has been removed from the interface;^[126] the "contentious" change was made because many websites depend on JavaScript and it was felt that users unaware that they had disabled JavaScript were attributing the resulting unpredictable layout to software bugs in Firefox.^[127]

The keyword.URL preference now is no longer supported, making it no longer possible to specify the search engine for the URL bar that way. The search engine selected for the search bar on the Navigation Toolbar is now automatically used also for the URL bar and about:home page.^[128][129]

Firefox 23.0.1 was released ten days later, August 16, 2013, to fix the rendering glitches on H.264 video only in FF23 on Windows Vista; it also fixed the spell checking that was broken with non-ASCII characters in profile path, and the audio static/"burble"/breakup in Firefox to Firefox WebRTC calls.^[130]

Version 24 (ESR)

Firefox 24 and Firefox 24 ESR were released on September 17, 2013. The release includes support for the new scrollbar style in Mac OS X 10.7 (and newer), closing tabs to the right, an improved browser console for debugging, and improved SVG rendering, among other things.^[131] Firefox 24 is the first version of the browser that uses SpiderMonkey 24.^[132]

Version 25

Firefox 25 was released on October 29, 2013. Firefox 25 Nightly was at one point slated to include the Australis theme, but Australis did not actually land on Nightly until Firefox 28,^[133] did not make it to Firefox 28 Aurora channel, and was finally available with Firefox 29.^[134] This release added support for <iframe srcdoc> attribute, background-attachment:local in CSS, along with Web audio API support, separate find bar for each tab and many other bug fixes.^{[135][136][137]}

Firefox 25.0.1 was released on November 15, 2013, to address issues with pages that sometimes wouldn't load without first moving the cursor.^[138]

Version 26

Firefox 26 was released December 10, 2013. Firefox 26 changed the behavior of Java plugins to "click-to-play" mode instead of automatically running them. It also added support for H.264 on Linux, password manager support for script-generated fields, and the ability for Windows users without advanced write permissions to update Firefox, as well as many bug fixes and developer-related changes.^[139]

Firefox 26.0.1 was released only for Android on December 20, just ten days after the desktop release. It fixed screen distortion on some devices after tapping on search suggestion.^[140]

Version 27

Firefox 27 was released on February 4, 2014. It adds improved Social API and SPDY 3.1 support, as well as enabling of TLS 1.1 and 1.2 by default. Also, it brings many bug fixes, security improvements, and developer-related changes.^[141]

Firefox 27.0.1 was released on February 13, 2014. It fixed stability issues with Greasemonkey and other JavaScript that used ClearTimeoutOrInterval, as well as JavaScript math correctness issues.^[142]

Version 28

Firefox 28 was released on March 18, 2014. It added support for VP9 video decoding and support for Opus in WebM.^[143] For Android, features such as predictive lookup from the address bar, quick share buttons and support for OpenSearch were added.^[144]

Firefox 28.0.1 was released only for Android six days later. It fixed H.264 video playback issues on several Galaxy devices and includes a mobile-only security fix for file: URLs.^[145]

Version 29

Firefox 29 was released on April 29, 2014 and includes the Australis interface; it also removes the add-on bar and moves its content to the navigation bar.^[146]

Firefox 29.0.1 was released ten days later, fixing a few bugs.^[147]

Version 30

Firefox 30 was released on June 10, 2014. It adds support for GStreamer 1.0 and a new sidebar button, and most plugins are not activated by default.^[148][149]

Version 31 (ESR)

Firefox 31 and Firefox 31 ESR were released on July 22, 2014. Both versions added search field on the new tab page and were improved to block malware from downloaded files, along with other new features.^[150] Firefox 31 ESR is the first ESR to include the Australis interface, unifying the user experience across different Firefox versions. Firefox 24.x.x ESR versions will be automatically updated to ESR version 31 after October 14, 2014.^[151]

Version 32

Firefox 32 was released on September 2, 2014. It shows off HTTP caching improvements, adds HiDPI/Retina support in the Developer Tools UI and widens HTML5 support, among other things.^[152][153] Firefox 32.0.1 was released for mobile only on September 10, fixing the link tap selection that is offset on some Android devices;^[154] and for desktop two days later, fixing stability issues.^[155] Firefox 32.0.2 was released for desktop only on September 18, fixing the corrupt installations causing Firefox to crash on update.^[156] Firefox 32.0.3 was released for desktop and Android on September 24, fixing a security vulnerability.^[157][158]

Version 33

Firefox 33 was released on October 14, 2014. It now has off-main-thread compositing (OMTC) enabled by default on Windows (which brings responsiveness improvements),^[159] OpenH264 support, search suggestions on about:home and about:newtab, address bar search improvements, session restore reliability improvements, and other changes.^[160]

Firefox 33.0.1 was released for desktop only on October 24, 2014, fixing displaying of a black screen at startup with certain graphics drivers.^[161] Firefox 33.0.2 was released for desktop only on October 28, 2014, fixing a startup crash with some combination of hardware and drivers.^[162] Firefox 33.0.3 was released for desktop only on November 6, 2014, fixing several issues related to graphics drivers.^[163]

Firefox 33.1 was released on November 10, 2014, celebrating Firefox's 10-year anniversary.^[164][165] Firefox 33.1.1 was released for desktop only on November 14, 2014, fixing a startup crash.^[166]

Version 34

Firefox 34.0 was released on December 1, 2014. It brings Firefox Hello (a WebRTC client for voice and video chat), an improved search bar, and the implementation of HTTP/2 (draft14) and ALPN, together with other features. It also disables SSLv3, and enables the ability to recover from a locked Firefox process and to switch themes and personas directly in the customization mode.^[167]

Firefox 34.0.5 was released for desktop only on December 1, 2014, changing the default search engine to Yahoo! for North America.^[168]

Version 35

Firefox 35.0 was released on January 13, 2015. It brings support for a room-based conversations model to the Firefox Hello chat service, and other functions; it includes security fixes.^[169]

Firefox 35.0.1 was released first for desktop on January 26, 2015, fixing various issues,^[170] and then for Android on February 5, 2015, fixing a crash with video playback on Asus MeMO Pad 10 and 8, Tesco Hudl, Lenovo Lifetab E models, and several other devices running the Rockchip SoC.^[171]

Version 36

Firefox 36.0 was released for desktop on February 24, 2015, bringing full HTTP/2 support and other smaller improvements and fixes.^[172] It was also released for Android three days later, adding support for the tablet user interface.^[173]

Firefox 36.0.1 was released for desktop on March 5, 2015, and the next day for Android, fixing various issues.^[174][175]

Firefox 36.0.2 was released for Android only on March 16, 2015, fixing a startup crash on HTC One M8 devices (Verizon) with Android 5.0.1 and some potential crashes with Flash videos.^[176]

Firefox 36.0.3 was released on March 20, 2015; soon after that, Version 36.0.4 was released on March 21, 2015, for desktop and Android, fixing security issues disclosed at HP Zero Day Initiative's Pwn2Own contest.^{[177][178][179][180]}

Version 37

Firefox 37 was released on March 31, 2015, bringing a heartbeat user rating system, which provides user feedback about the Firefox, and improved protection against website impersonation via OneCRL centralized certificate revocation. Also, Bing search is changed to use HTTPS for secure searching, and added is support for opportunistic encryption of the HTTP traffic where the server supports HTTP/2's AltSvc feature.^[181]

Firefox 37.0.1 was released on April 3, 2015 for desktop and Android, fixing security issues and several crash issues. It also disabled opportunistic encryption of the HTTP traffic introduced in 37.0.^[182][183]

Firefox 37.0.2 was released for Android on April 14, 2015, fixing an issue related to the "request desktop site" feature,^[184] and for desktop on April 20, 2015, fixing a Google Maps rendering issue, stability issues for some graphics hardware and feature sets, and certain security issues.^[185]

Version 38 (ESR)

Both Firefox 38 and Firefox 38 ESR were released on May 12, 2015, with new tab-based preferences, Ruby annotation support and availability of WebSockets in web workers, along with the implementation of the BroadcastChannel API and other features and security fixes.^[186]

Firefox 38.0.1 and ESR 38.0.1 were released on May 14, 2015 for desktop, fixing a number of stability issues.^[187] Firefox 38.0.1 for Android was released on May 15, 2015, fixing a number of stability issues.^[188]

Firefox 38.0.5 was released on June 2, 2015 for desktop and Android, fixing bugs and security issues, and adding new functionality that included integration of Pocket and availability of Reader View mode.^[189][190] This was the first release offered to the Release channel users since 38.0.1.

Version 39

Firefox 39 was released on July 2, 2015 for desktop and Android, disabling insecure SSLv3 and RC4, improving performance for IPv6 fallback to IPv4 and including various security fixes.^[191][192] Firefox 39.0.3 was released on August 6, 2015, to fix a zero-day exploit.^[193]

Version 40

Firefox 40 was released on August 11, 2015 for desktop and Android. On Windows 10, the Australis theme was updated to reflect the overall appearance of Windows 10, and the interface is adapted for usability on touchscreens when used in the operating system's "Tablet mode". Firefox 40 includes additional security features, including the filtering of pages that offer potentially unwanted programs, and warnings during the installation of unsigned extensions; in future versions, signing of extensions will become mandatory, and the browser will refuse to install extensions that have not been signed. Firefox 40 also includes performance improvements, such as off-main-thread compositing on Linux.^{[194][195][196]}

Firefox 40.0.2 was released for desktop only two days later on August 13, fixing some stability issues.^[197]

Firefox 40.0.3 was released for desktop and Android on August 27, fixing some stability issues and security vulnerabilities.^[198][199]

Version 41

Firefox 41 was released on September 22, 2015 for desktop and Android. Among many additions are the ability to set a profile picture for a Firefox account, enhanced IME support using Text Services Framework, and instant messaging on Firefox Hello.^[200][201]

Firefox 41.0.1 was released for desktop only on September 30, 2015, fixing some stability issues.^[202]

Firefox 41.0.2 was released on October 15, 2015, fixing a security vulnerability.^[203]

Version 42

Firefox 42 was released on November 3, 2015 for desktop and Android. Among many additions are private browsing with tracking protection, IPv6 support in WebRTC, and the ability to view HTML source in a tab.^[204][205]

Version 43

Firefox 43 was released on December 15, 2015 for desktop and Android. Among many additions are the availability of the 64-bit version for Windows 7 and above users, a new strict blocklist, and audio indicators on Android.^[206][207]

Firefox 43.0.1 was released on December 18, 2015 for desktop only, to prepare for the use of SHA-256 signing certificate for Windows builds, to meet a new signing requirement.^[208] Three days later, Firefox 43.0.2 was released for desktop only, citing not only the use of SHA-256 signing certificate for Windows builds, but also various security fixes.^[209] Firefox 43.0.3 was released for desktop only on December 28, 2015, fixing a network issue when using Nvidia's Network Access Manager, and improving the decoding of some videos on YouTube on some Windows configurations.^[210] Firefox 43.0.4 was released for desktop only on January 6, 2016, fixing a startup crash for users of a third party antivirus tool, allowing the creation of multi-user GNU/Linux download folders, and re-enabling SHA-1 certificates.^[211]

Version 44

Firefox 44 was released on January 26, 2016 for desktop and Android. Among many additions are the improvement of warning pages for certificate errors and untrusted connections, enabling of H.264 and WebM/VP9 video support on systems that don't support MP4/H.264, support for the brotli compression format via HTTPS content-encoding, and the use of Android print service to enable cloud printing.^[212][213] "Ask me every time" cookies option was removed without any notifications.^[214]

Firefox 44.0.1 was released on February 8, 2016 for desktop only, fixing an issue that could lead to the removal of stored passwords under certain circumstances; requiring NSS 3.21; and disabling opus/vorbis audio with H.264, among other things.^[215] Firefox 44.0.2 was released three days later for desktop and Android, fixing issues where Firefox hangs or crashes on startup among other issues.^[216][217]

Version 45 (ESR)

Firefox 45 and Firefox 45 ESR were released on March 8, 2016 for desktop (both) and Android (no ESR). Among many additions were Instant Browser sharing through Hello, the addition of Guarani locale, the ability to filter snapshot output in memory tool, and the removal of Tab Groups (panorama) feature.^[218][219] Firefox 45.0.1 and Firefox 45.0.1 ESR were released on March 16, 2016 for desktop (both) and Android (no ESR). Several regressions are fixed and Graphite library is disabled.^[220][221] Firefox 45.0.2 and Firefox 45.0.2 ESR were released on April 11, 2016 for desktop (both) and Android (no ESR). Many fixes included are for the cookie header, compatibility regression (both), and a regression with the copy and paste with some old versions of some Gecko applications like Thunderbird (desktop only).^[222][223]

Version 46

Firefox 46 was released on April 26, 2016 for both desktop and Android. Among the many additions were improved security of the JavaScript Just In Time (JIT) Compiler, the GTK3 integration (GNU/Linux only), HKDF support for Web Crypto API, and removal of support for Android 3.0 (Android only).^[224][225]

Firefox 46.0.1 was released on May 3, 2016 for both desktop and Android, fixing various issues, including add-on signing certificate expiration and page loading issue related to antivirus software.^[226][227]

Version 47

Firefox 47 was released on June 7, 2016 for both desktop and Android. Among the many additions were support for Google’s Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video; enabling VP9 video codec for users with fast machines; the ability of embedded YouTube videos to play with HTML5 video if Flash is not installed; and the addition of the Latgalian language. It is also the last Firefox version to support Mac OS X Snow Leopard, Mac OS X Lion, OS X Mountain Lion, and Android 2.3.x.^[228][229]

Firefox 47.0.1 was released on June 28, 2016 for desktop only, which fixed an issue with the Selenium WebDriver.^[230]

Version 48

Firefox 48 was released on August 2, 2016 for both desktop and Android. Among the many additions were enhanced download protection and the removal of Windows Remote Access Service modem Autodial. Starting with this version, Mac OS X support is exclusively for OS X Mavericks up to macOS Sierra.^[231][232] Additionally, support for old processors without SSE2 extensions such as the AMD Athlon XP and Pentium III was dropped.^[231]

Firefox 48.0.1 was released on August 18, 2016 for desktop only, fixing a top crash in the JavaScript engine, another one caused by plugin issues, a shutdown issue, and other bugs.^[233] Firefox 48.0.2 was released six days later for desktop only, which fixed a Windows-only startup crash issue caused by Websense.^[234]

Version 49

Firefox 49 was released on September 20, 2016 for both desktop and Android. Among the many additions were an updated Firefox Login Manager, improved video performance for users on systems that support SSE3 without hardware acceleration, added context menu controls to HTML5 audio and video that let users loop files or play files at 1.25x speed, improvements in about:memory reports for tracking font memory usage, and the removal of Firefox Hello.^[235][236]

Firefox 49.0.1 was released three days later for desktop only, mitigating a Windows-only startup crash issue caused by Websense.^[237]

Firefox 49.0.2 was released for both desktop and Android on October 20, 2016; among the changes are asynchronous rendering of the Flash plugins that is now enabled by default (desktop), and the fix for web compatibility issue with file uploads (Android).^[238][239]

Version 50

Firefox 50 was released on November 15, 2016 for both desktop and Android. Among the many additions were playback video on more sites without plugins with WebM EME Support for Widevine on Windows and Mac; improved performance for SDK extensions or extensions using the SDK module loader; download protection for a large number of executable file types on Windows, Mac and Linux; increased availability of WebGL to more than 98 percent of users on Windows 7 and newer (desktop); and support for HLS videos via player overlay (Android).^[240][241]

Firefox 50.0.1 was released on November 28, 2016 for desktop only, fixing an issue where Firefox crashes with 3rd party Chinese IME when using IME text.^[242] Firefox 50.0.2 was released two days later for both desktop and Android, fixing a zero-day exploit in the wild among other exploits.^[243][244]

Extended Support Release

In January 2012, the Mozilla Foundation announced the availability of an Extended Support Release (ESR) version of Firefox.^[245] In addition to the "release", "beta", and "aurora" update channels the ESR versions form the "esr" update channel.

Firefox ESR is intended for groups who deploy and maintain the desktop environment in large organizations such as universities and other schools, county or city governments and businesses. During the extended cycle, no new features will be added to a Firefox ESR; only high-risk/high-impact security vulnerabilities or major stability fixes will be corrected.^[246]

An Extended Support Release includes continuity of support through 9 normal Firefox rapid release cycles (54 weeks), with the final 2 cycles overlapping the next version. ESR versions will jump from 10 to 17, then to 24 etc.^[246]

Every six weeks when a new mainstream Firefox release is made under the rapid release cycle, a corresponding security update would also be released for the then-current ESR version. For example, ESR 10.0.1 would be expected to be released at the same time as Firefox 11, ESR 10.0.2 at the same time as Firefox 12. Security updates for ESR versions are also released when out-of-band security updates are made available for mainstream Firefox releases, for example ESR 10.0.10 corresponds with Firefox 16.0.2. At Firefox 17 and Firefox 18, there would be two ESR versions supported. Respectively, ESR 10.0.11 and ESR 17.0.0; ESR 10.0.12 and ESR 17.0.1. Finally, when Firefox reaches 19.0, ESR 10 would go end-of-life alongside the release of ESR 17.0.2. The cycle repeats again.

After the end-of-life with ESR 10.0.12 the Firefox Updater suggested to update to ESR 17.0.x on supported platforms.

The numbering scheme changed somewhat starting with ESR 24.0.0 series. The first minor version number increments on regularly scheduled six-week release cycle, and the second minor version number increments when unscheduled off-cycle releases are necessary. For example, ESR 24.1.0 was released at the same time as 25.0.0, ESR 24.1.1 was released at the same time as 25.0.1, and ESR 24.2.0 was released at the same time as 26.0.0.^[247]

Version history

As of November 15, 2016, Firefox 51 beta is in the "Beta" channel, Firefox 52 alpha is in the "Aurora" channel, and Firefox 53 pre-alpha is in the "Nightly" (Central) channel.

Color	Significance
Red	Former release; no longer supported
Yellow	Former release; still supported
Green	Current supported release

Release history

Version	Release date	Gecko version	Release notes
0.1	September 23, 2002	1.2	First release[248]
0.2	October 1, 2002		Web form auto-complete Sidebar is back Downloads Sidebar Bookmarks Sidebar History Sidebar Extension management Toolbar customization Search bar Improved preference defaults Speed improvements Ctrl+Mousewheel to resize fonts Bug fixes[249]
0.3	October 14, 2002		Image Blocking Pop-up Blocking Whitelist Bookmarks Changes Global Go Menu and Other Menu Changes Tabbed Browsing Improvements Size and Speed Improvements Bug fixes[250]
0.4	October 19, 2002	1.3	Improvements to pop-up blocking Improvements to toolbar customization Improvements to tabbed browsing and shortcut keys Type ahead find returns Address bar gets smarter Themes Bug fixes[251]
0.5	December 7, 2002		Multiple homepages Intellimouse 5-button support Sidebar remembers its state across sessions Download fixes History improvements Accessibility improvements Size and memory reduction Performance improvements Stability improvements Better Windows appearance Many more new themes Many bug fixes[252]
0.6	May 17, 2003	1.5	New default theme Redesigned Preferences window Improved Privacy Options Improved Bookmarks Talkback enabled to tell Mozilla why the browser crashed Automatic Image Resizing Smooth Scrolling Access to more preferences through about:config Custom profile save location Mac OS X compatibility Lots of bug fixes[253]
0.7	October 15, 2003		Advanced preferences panel Download/helper apps preferences panel Cookie whitelisting New password manager (all passwords now stored encrypted[254]) Web panels (like Mozilla's sidebar panels) Alternate stylesheet support (through a status bar button) Send Page, Send Link, and Send Image menu items Autoscroll Lots of bug fixes and other small improvements[255]
0.8	February 9, 2004	1.6	Windows Installer Download Manager New Add Bookmark Dialog Work Offline Better Handling of File Types New XPInstall Frontend New default theme for Mac OS X Lots of bug fixes and improvements [256]
0.9	May 15, 2004	1.7	New Default Theme Comprehensive Data Migration from Internet Explorer Extension/Theme Manager Smaller Download Online help system Lots of bug fixes and improvements[257]
1.0	November 9, 2004		Better Tabbed Browsing Controls Horde of bug fixes[258]
1.0.8	April 13, 2006		Security fixes Bug fixes Stability fixes[259]
1.5	November 29, 2005	1.8	Dropped support for Mac OS X v10.1, minimum is now Mac OS X v10.2 Private data clear data Back and forward now fast Improved web standards Improved HTML Improved CSS Improved HTTP Improved JavaScript/DOM SVG compatibility Huge amount of bug fixes[260]
1.5.0.12	May 30, 2007		Last release for Windows 95 Bug fixes Stability fixes Security fixes[261]
2.0	October 24, 2006	1.8.1	Visual Refresh of main theme Built-in phishing protection Enhanced search capabilities Improved tabbed browsing Resuming your browsing session (session restore) Previewing and subscribing to Web feeds Inline spell checking Live Web Titles Improved Add-ons manager JavaScript 1.7 Extended search plugin format (predictive search) Improved security with extension system Client-side session and persistent storage SVG text support New Windows installer[262]
2.0.0.20	December 18, 2008		Last release for Windows NT 4.0, 98, Me. Bug fixes Security fixes Stability fixes[263]
3.0	June 17, 2008	1.9	One-click site info Malware Protection New Web Forgery Protection page New SSL error pages Add-ons and Plugin version check Secure add-on updates Anti-virus integration with download manager Vista Parental Controls Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain. Better protection against cross-site JSON data leaks. Easier password management – save passwords after successful login Simplified add-on installation from third party’s New Download Manager Resumable downloading after closing the browser Full page zoom Podcasts and Videocasts can be associated with your media playback tools Tab scrolling and quickmenu Save what you were doing - Firefox 3 will prompt users to save tabs on exit. Optimized Open in Tabs behavior Location and Search bar size can now be customized with a simple resizer item. Text selection improvements (select multiple selections of text) Find toolbar: the Find toolbar now opens with the current selection. Plugin management with the add-on manager Improved integration with Windows Improved integration with the Mac Integration with Linux GTK theme Bookmark star button Bookmark tags Smart Location Bar Library of bookmarks, history, etc. Smart Bookmark Folders Web-based protocol handlers for mail:to Download & Install Add-ons from the Add-on manager Easy to use Download Actions New graphics and font handling in Gecko 1.9 provide rendering improvements in: CSS SVG Display of fonts with ligatures and complex scripts Color management of images with capabilities Offline support for web applications Improved speed Reduced memory usage Increased reliability 25000 total code changes Security fixes Stability fixes[264]
3.0.19	March 30, 2010		Fixed several security problems. Fixed several stability issues.[265]
3.5	June 30, 2009	1.9.1	Support for the HTML5 <video> and <audio> elements including native support for Ogg Theora video and Vorbis audio Improved tools for controlling your private data, including a Private Browsing Mode Better web application performance using the new TraceMonkey JavaScript engine The ability to share your location with websites using Location Aware Browsing Support for native JSON, and web worker threads Improvements to the Gecko layout engine, including speculative parsing for faster content rendering Support for new web technologies such as: Downloadable fonts CSS media queries New transformations and properties JavaScript query selectors HTML5 local storage and offline application storage <canvas> text ICC profiles SVG transforms.[266]
3.5.19	April 28, 2011		Fixed several security issues Fixed several stability issues[267]
3.6	January 21, 2010	1.9.2	Support for Persona themes Protection from out-of-date plugins to keep users safer as they browse. Open, native video can now be displayed full screen and supports poster frames. Improved JavaScript performance, overall browser responsiveness, and startup time. The ability for web developers to indicate that scripts should run asynchronously to speed up page load times. Continued support for downloadable web fonts using the new WOFF font format. Support for new CSS attributes such as gradients, background sizing, and pointer events. Support for new DOM and HTML5 specifications including the Drag & Drop API and the File API, which allow for more interactive web pages. Changes to how third-party software can integrate with Firefox in order to prevent crashes.[268]
3.6.28	March 13, 2012		Last release for Mac OS X Tiger and PowerPC Macs Added Out-of-process plugins[269] Fixed several security issues Fixed several stability issues[270]
4.0	March 22, 2011	2.0	Firefox 4 is available in over 80 languages Uses JägerMonkey, a faster JavaScript engine Support for Do Not Track ("DNT") header that allows users to opt out of behavioral advertising Firefox Sync is included by default Graphic rendering is now hardware-accelerated using Direct3D 9 (Windows XP), Direct3D 10 (Windows Vista & 7), and OpenGL on Mac OS Direct2D Hardware Acceleration is now on by default for Windows 7 users WebGL is enabled on all platforms that have a capable graphics card with updated drivers Native support for the HD HTML5 WebM video format, hardware accelerated where available Firefox button has a new look for Windows Vista and Windows 7 users Tabs are now on top by default on Windows, Mac OS X, and Linux You can search for and switch to already open tabs in the Smart Location Bar The stop and reload buttons have been merged into a single button on Windows, Mac OS X, and Linux The Bookmarks Toolbar has been replaced with a Bookmarks Button by default (you can switch it back if you'd like) Crash protection when there is a crash in Adobe Flash Player, Apple QuickTime or Microsoft Silverlight plugins You can turn any tab into an "App Tab" The default homepage design has been refreshed Overhaul of the bookmarks and history code, enabling faster bookmarking and startup performance Per-compartment garbage collection is now enabled, reducing work done during complex animations Additional polish for the Firefox add-on Manager Improved web typography using OpenType with support for ligatures, kerning and font variants Web developers can animate content using CSS Transitions Responsiveness and scrolling improvements from the new retained layers layout system HTML5 Forms API makes web based forms easier to implement and validate Support for the new proposed Audio Data API Support for HSTS security protocol allowing sites to insist that they only be loaded over SSL A new feature called Panorama gives users a visual overview of all open tabs, allowing them to be sorted and grouped An experimental API is included to provide more efficient JavaScript animations Firefox now supports the HTML5 video "buffered" property Changes to how XPCOM components are registered in order to help startup time and process separation New Addons Manager and extension management API Significant API improvements are available for JS-ctypes, a foreign function interface for extensions CSS Transitions are partially supported Core Animation rendering model for plugins on Mac OS X Web developers can update the URL field without reloading the page using HTML History APIs More responsive page rendering using lazy frame construction Link history lookup is done asynchronously to provide better responsiveness during pageload CSS :visited selectors have been changed to block websites from being able to check a user's browsing history New HTML5 parser Support for more HTML5 form controls Web authors can now get touch events from Firefox users on Windows 7 machines A new way of representing values in JavaScript that allows Firefox to execute heavy, numeric code more efficiently[271]
4.0.1	April 28, 2011		Fixed several security issues Fixed several stability issues[272]
5.0	June 21, 2011	5.0	Better standards support for HTML5, CSS3, MathML, XHR and SMIL Better visibility for the Do not track header preference[273] Stability and security improvements[274][275][276] Better tuned HTTP idle connection logic[273] Improved canvas, JavaScript, memory, and networking performance Improved spell checking for some locales Improved desktop environment integration for Linux users Better WebGL security (WebGL content can no longer load cross-domain textures).[277] Background tabs have setTimeout and setInterval clamped to 1000 ms to improve performance[278] Gecko version number bumped to 5.0 to match (and from then on stay synced to) Firefox's major version number[279]
5.0.1	July 11, 2011		Fixed an issue in Mac OS X 10.7 that could cause Firefox to crash[280] Fixed an issue caused by Apple's "Java for Mac OS X 10.6 Update 5" where the Java plugin would not be loaded[281]
6.0	August 16, 2011	6.0	about:permissions, a permissions manager. The user can choose what information can be shared with sites, e.g. location. The address bar now highlights the domain of the website you are visiting. Streamlined the look of the site identity block Added support for the latest draft version of WebSockets with a prefixed API Added support for EventSource / server-sent events Added support for window.matchMedia Added Scratchpad, an interactive JavaScript prototyping environment Added a new Web Developer menu item and moved development-related items into it Improved usability of the Web Console Improved the discoverability of Firefox Sync Reduced browser startup time when using Panorama Fixed several stability issues Fixed several security issues[282]
6.0.2	September 6, 2011		Revoked the root certificate for DigiNotar due to fraudulent SSL certificate issuance[283] Removed trust exceptions for certificates issued by Staat der Nederlanden Resolved an issue with gov.uk websites[284]
7.0	September 27, 2011	7.0	Drastically improved memory handling for certain use cases Added a new rendering backend to speed up Canvas operations on Windows systems Bookmark and password changes now sync almost instantly when using Firefox Sync The 'http://' URL prefix is now hidden by default. Added support for text-overflow: ellipsis Added support for the Web Timing specification Enhanced support for MathML The WebSocket protocol has been updated from version 7 to version 8. Added an opt-in system for users to send performance data back to Mozilla to improve future versions of Firefox Fixed several stability issues Fixed several security issues[285]
7.0.1	September 29, 2011		Fixed a rare issue where some users could find one or more of their add-ons hidden after a Firefox update[286]
8.0	November 8, 2011	8.0	Add-ons installed by third-party programs are now disabled by default Added a one-time add-on selection dialog to manage previously installed add-ons Added Twitter to the search bar Added a preference to load tabs on demand, improving startup time when windows are restored Improved performance and memory handling when using <audio> and <video> elements Added Cross-Origin Resource Sharing (CORS) support for cross-domain textures in WebGL Added support for HTML5 context menus Added support for insertAdjacentHTML() Improved CSS hyphen support for many languages Improved WebSocket support Fixed several stability issues[287]
8.0.1	November 21, 2011		Fixed Mac OS X crash that occurred in certain instances when a Java Applet is loaded with Java SE 6 version 1.6.0_29 installed. Fixed Windows startup crash caused by RoboForm versions older than 7.6.2.[288]
9.0	December 20, 2011	9.0	Added type inference, significantly improving JavaScript performance. Improved theme integration for Mac OS X Lion. Added two finger swipe navigation for Mac OS X Lion. Added support for querying Do Not Track status via JavaScript. Added support for the font-stretch CSS property. Improved support for the text-overflow CSS property. Improved standards support for HTML5, MathML, and CSS. Fixed several stability issues.[289]
9.0.1	December 21, 2011		Fixed crash on Windows, Mac and Linux[290]
10.0	January 31, 2012	10.0	Most add-ons are now compatible with new versions of Firefox by default. Anti-Aliasing for WebGL is now implemented. CSS3 3D-Transforms are now supported. New element for bi-directional text isolation, along with supporting CSS properties. Full Screen APIs allow you to build a web application that runs full screen.[291]
10.0.1	February 10, 2012		Security fix[292]
10.0.2	February 16, 2012		Fixed Java applets that sometimes caused text input to become unresponsive.[293]
10.0.3esr	March 13, 2012		Security fixes[294] Fixed web workers running out of memory, affecting some add-ons used by organizations.[295]
10.0.4esr	April 24, 2012		Fixed an issue in Firefox ESR 10.0.3 that caused the "Whats New" page to open after an update. Fixed extensions.checkCompatibility.* prefs not working in ESR releases.[296]
10.0.5esr	June 5, 2012		Fixed the 10.0.5 Firefox top crash with signature [@ GLEngine@0x620cf ].[297]
10.0.6esr	July 17, 2012		Security fixes Stability fixes Fixed some text editing inconsistencies.[298]
10.0.7esr	August 28, 2012		Fixed contenteditable breaks in 10.0.7 that middle-click to open links Addressed a fix that allows specifying wildcard that matches all simple netbiosnames in network.automatic-ntlm-auth.trusted-uris.[299]
10.0.8esr	October 9, 2012		Security fixes[300]
10.0.9esr	October 12, 2012		Security fix[300]
10.0.10esr	October 26, 2012		Security fix[300]
10.0.11esr	November 20, 2012		Security fix[301]
10.0.12esr	January 8, 2013		Security fix[302]
11.0	March 13, 2012	11.0	Migration of settings from Google Chrome SPDY protocol support (disabled by default) RFC 6455 WebSocket protocol support with an unprefixed API Page Inspector Tilt (3D View) Sync Add-ons Redesigned HTML5 video controls Style Editor (CSS)[303]
12.0	April 24, 2012	12.0	Windows: Firefox is now easier to update with one less prompt (User Account Control) Last release for Windows 2000 Reintroduced on-demand loading of pinned tabs after restoring a session Page Source now has line numbers Line breaks are now supported in the title attribute Improvements to "Find in Page" to center search result URLs pasted into the download manager window are now automatically downloaded Support for the text-align-last CSS property has been added Experimental support for ECMAScript 6 Map and Set objects has been implemented Various security fixes Many bug fixes Some TinyMCE-based editors failed to load (739141) OS X: WebGL performance may be degraded on some hardware (713305)[304]
13.0	June 5, 2012	13.0	When opening a new tab, users are now presented with their most visited pages The default home page now has quicker access to bookmarks, history, settings, and more SPDY protocol now enabled by default for faster browsing on supported sites Restored background tabs are not loaded by default for faster startup Smooth scrolling is now enabled by default 72 total improvements to Page Inspector, HTML panel, Style Inspector, Scratchpad and Style Editor The column-fill CSS property has been implemented Experimental support for ECMAScript 6 Map and Set objects has been implemented Support for the CSS3 background-position property extended syntax has been added The :invalid pseudo-class can now be applied to the element The CSS turn angle unit is now supported[305]
13.0.1	June 15, 2012		Fixed an issue when Windows Messenger did not load in Hotmail, and the Hotmail inbox did not auto-update Fixed the Hebrew text that was sometimes rendered incorrectly Fixed an issue in Adobe Flash 11.3 that sometimes caused a crash on quit Various security fixes[306]
14.0	June 26, 2012	14.0	Google searches now utilize HTTPS Full screen support for Mac OS X Lion implemented Plugins can now be configured to only load on click (about:config) The Awesome Bar now auto-completes typed URLs Improved site identity manager, to prevent spoofing of an SSL connection with favicons Pointer Lock API implemented New API to prevent your display from sleeping New text-transform and font-variant CSS improvements for Turkic languages and Greek[307][308] Long URLs now extend the status bar almost to the whole width of the viewport. Gstreamer backend for HTML5 video to allow H.264 playback (needs to be enabled at compile time).
14.0.1	July 17, 2012		Various security fixes Fixed the GIF animation that can get stuck when src and image size are changed Mac OS X: Fixed the nsCocoaWindow::ConstrainPosition that uses wrong screen in multi-display setup Fixed the CSS :hover regression when an element's class name is set by JavaScript[309]
15.0	August 28, 2012	15.0	Silent update: Background updates Support for SPDY networking protocol v3 WebGL enhancements, including compressed textures for better performance Localization in Maithili Optimized memory usage for add-ons JavaScript debugger integrated into developer tools New layout view added to Inspector High precision event timer implemented The CSS word-break property has been implemented New responsive design tool allows web developers to switch between desktop and mobile views of sites Native support for the Opus audio format added The <audio> and <video> elements now support the played attribute The source element now supports the media attribute Fixed the focus rings that keep growing when repeatedly tabbing through elements[310]
15.0.1	September 6, 2012		Addressed a fix where sites visited while in Private Browsing mode could be found through manual browser cache inspection[311]
16.0	October 9, 2012	16.0	Firefox on Mac OS X now has preliminary VoiceOver support turned on by default Last release for Mac OS X Leopard (Intel) Initial web app support (Windows/Mac/Linux) Acholi and Kazakh localizations added Improvements around JavaScript responsiveness through incremental garbage collection New Developer Toolbar with buttons for quick access to tools, error count for the Web Console, and a new command line for quick keyboard access CSS3 Animations, Transitions, Transforms and Gradients unprefixed Recently opened files list in Scratchpad implemented Fixed an issue where debugger breakpoints do not catch on page reload No longer supporting MD5 as a hash algorithm in digital signatures Opus support by default Reverse animation direction has been implemented Per tab reporting in about:memory User Agent strings for pre-release Firefox versions now show only major version[312]
16.0.1	October 11, 2012		Fixed security vulnerabilities[313]
16.0.2	October 26, 2012		Fixed security vulnerability[314]
17.0	November 20, 2012	17.0	First revision of the Social API and support for Facebook Messenger Click-to-play blocklisting implemented to prevent vulnerable plugin versions from running without the user's permission Updated Awesome Bar experience with larger icons Mac OS X 10.5 is no longer supported JavaScript Maps and Sets are now iterable SVG FillPaint and StrokePaint implemented Improvements that make the Web Console, Debugger and Developer Toolbar faster and easier to use New Markup panel in the Page Inspector allows easy editing of the DOM Sandbox attribute for iframes implemented, enabling increased security Over twenty performance improvements, including fixes around the New Tab page Fixed pointer lock that doesn't work in web apps Fixed page scrolling on sites with fixed headers[315]
17.0.1	November 30, 2012		Reverted user agent change causing some website incompatibilities Fixed font rendering issue[316]
17.0.2esr	January 8, 2013		Security and stability fixes Fixed improvements to the Click-to-Play vulnerable plugin blocklisting feature[317]
17.0.3esr	February 19, 2013		Security fix[318]
17.0.4esr	March 7, 2013		Security fix[319]
17.0.5esr	April 2, 2013		Security fix[320]
17.0.6esr	May 14, 2013		Security fix[321]
17.0.7esr	June 25, 2013		Security fix[322]
17.0.8esr	August 6, 2013		Security fix[323]
17.0.9esr	September 17, 2013		Security fix[324]
17.0.10esr	October 29, 2013		Security fix[325]
17.0.11esr	November 15, 2013		Updated ESR17 to NSS 3.14.5 RTM.[326]
18.0	January 8, 2013	18.0	Faster JavaScript performance via IonMonkey compiler Support for Retina displays on OS X 10.7 and up Preliminary support for WebRTC Better image quality with Mozilla's new HTML scaling algorithm Performance improvements around tab switching Support for new DOM property window.devicePixelRatio Improvement in startup time through smart handling of signed extension certificates Support for W3C touch events implemented, taking the place of MozTouch events Disable insecure content loading on HTTPS pages Improved responsiveness for users on proxies[327]
18.0.1	January 18, 2013		Fixed problems involving HTTP Proxy Transactions Fixed unity player crashes on Mac OS X Disabled HIDPI support on external monitors to avoid rendering glitches[328]
18.0.2	February 5, 2013		Fixed JavaScript related stability issues[329]
19.0	February 19, 2013	19.0	Built-in PDF Viewer Canvas elements can export their content as an image blob using canvas.toBlob() Startup performance improvements Debugger now supports pausing on exceptions and hiding non-enumerable properties Remote Web Console is available for connecting to Firefox on Android or Firefox OS (experimental, set devtools.debugger.remote-enabled to true) There is now a Browser Debugger available for add-on and browser developers (experimental, set devtools.chrome.enabled to true) Web Console CSS links now open in the Style Editor CSS @page is now supported CSS viewport-percentage length units implemented (vh, vw, vmin and vmax) CSS text-transform now supports full-width Fixed certain valid WebGL drawing operations that were incorrectly rejected, leaving incomplete rendering in affected pages Fixed an issue that starting Firefox with -private flag incorrectly claims you are not in Private Browsing mode Fixed plugins that stop rendering when the top half of the plugin is scrolled off the top of the page, in HiDPI mode[330]
19.0.1	February 27, 2013		Windows 8 only: Fixed stability issue for some AMD Radeon HD graphics cards[119]
19.0.2	March 7, 2013		Security-driven release[120]
20.0	April 2, 2013	20.0	Security fixes Per-window Private Browsing New download experience Ability to close hanging plugins, without the browser hanging Continued performance improvements around common browser tasks (page loads, downloads, shutdown, etc.) Continued implementation of draft ECMAScript 6 - clear() and Math.imul New JavaScript Profiler tool getUserMedia implemented for web access to the user's camera and microphone (with user permission) <canvas> now supports blend modes Various <audio> and <video> improvements Fixed: Details button on Crash Reporter Fixed: Unity plugin that doesn't display in HiDPI mode[331]
20.0.1	April 11, 2013		Windows-only update to handle issues around handling UNC paths[332]
21.0	May 14, 2013	21.0	The Social API now supports multiple providers Enhanced three-state UI for Do Not Track (DNT) Preliminary implementation of Firefox Health Report Firefox will suggest how to improve your application startup time if needed Ability to Restore removed thumbnails on New tab Page CSS -moz-user-select:none selection changed to improve compatibility with -webkit-user-select:none Graphics related performance improvements Removed E4X support from SpiderMonkey Implemented Remote Profiling Integrated, Add-on SDK loader and API libraries into Firefox Added support for <main> element Implemented scoped stylesheets Fixed: Some function keys may not work when pressed Fixed: Browsing and Download history clearing needs unification to avoid confusion on clearing download history Security fixes[333]
22.0	June 25, 2013	22.0	WebRTC is now enabled by default Windows: Firefox now follows display scaling options to render text larger on high-res displays Mac OS X: Download progress in Dock application icon HTML5 audio/video playback rate can now be changed Social services management implemented in Add-ons Manager asm.js optimizations (OdinMonkey) enabled for major performance improvements Improved WebGL rendering performance through asynchronous canvas updates Plain text files displayed within Firefox will now word-wrap For user security, the |Components| object is no longer accessible from web content Improved memory usage and display time when rendering images Pointer Lock API can now be used outside of fullscreen CSS3 Flexbox implemented and enabled by default New Web Notifications API implemented Added clipboardData API for JavaScript access to a user's clipboard New built-in font inspector New HTML5 <data> and <time> elements Fixed: Scrolling using some high-resolution-scroll aware touchpads feels slow[334]
23.0	August 6, 2013	23.0	Mixed content blocking enabled to protects users from man-in-the-middle attacks and eavesdroppers on HTTPS pages Options panel created for Web Developer Toolbox "Enable JavaScript" preference checkbox has been removed and user-set values will be reset to the default Updated Firefox Logo Improved about:memory's functional UI Simplified interface for notifications of plugin installation Enabled DXVA2 on Windows Vista+ to accelerate H.264 video decoding Users can now switch to a new search provider across the entire browser CSP policies using the standard syntax and semantics will now be enforced <input type='file'> rendering improvements Replaced fixed-ratio audio resampler in webrtc.org capture code with Speex resampler and eliminated pseudo-44,000 Hz rate "Load images automatically" and "Always show the tab bar" checkboxes removed from preferences and reset to defaults HTML5 <input type="range"> form control implemented Write more accessible pages on touch interfaces with new ARIA role for key buttons Social share functionality Added unprefixed requestAnimationFrame Implemented a global browser console Dropped blink effect from text-decoration: blink; and completely removed <blink> element New feature in toolbox: Network Monitor Various security fixes[335]
23.0.1	August 16, 2013		Fixed rendering glitches on H.264 video only in FF23 on Vista Fixed spellchecking that was broken with non-ASCII characters in profile path Fixed audio static/"burble"/breakup in Firefox to Firefox WebRTC calls[336]
24.0	September 17, 2013	24.0	Support for new scrollbar style in Mac OS X 10.7 and newer Implemented Close tabs to the right Social: Ability to tear-off chat windows to view separately by simply dragging them out Accessibility related improvements on using pinned tabs Removed support for Revocation Lists feature Performance improvements on New Tab Page loads Major SVG rendering improvements around Image tiling and scaling Improved and unified Browser console for enhanced debugging experience, replacing existing Error console Removed support for sherlock files that are loaded from application or profile directory Replaced fixed-ratio audio resampler in webrtc.org capture code with Speex resampler and eliminated pseudo-44,000  rate Security fixes[337]
24.1.0esr	October 29, 2013		Security fix[338]
24.1.1esr	November 15, 2013		Updated branches that use 4.10 RTM to 4.10.2 RTM Updated Mozilla to NSS 3.15.3 (new alternative NSS branch) to pick up a few fixes Fixed an issue where some UI strings in Firefox 24.1.0 ESR l10n builds are in English[339]
24.2.0esr	December 10, 2013		Security fix[340]
24.3.0esr	February 4, 2014		Security fix[341]
24.4.0esr	March 18, 2014		Security fix[342]
24.5.0esr	April 29, 2014		Security fix[343]
24.6.0esr	June 10, 2014		Security fix[344]
24.7.0esr	July 22, 2014		Security fix[345]
24.8.0esr	September 2, 2014		Security fix[346]
24.8.1esr	September 24, 2014		Various security fixes[347]
25.0	October 29, 2013	25.0	Web Audio support The find bar is no longer shared between tabs If away from Firefox for months, you now will be offered the option to migrate another browser's history and settings Resetting Firefox no longer clears your browsing session CSS3 background-attachment:local support to control background scrolling Many new ES6 functions implemented iframe document content can now be specified inline Fixed blank or missing page thumbnails when opening a new tab[348]
25.0.1	November 15, 2013		Security fixes Fixed pages that sometimes wouldn't load without first moving the cursor[349]
26.0	December 10, 2013	26.0	All Java plug-ins are defaulted to 'click to play' Password manager now supports script-generated password fields Updates can now be performed by Windows users without write permissions to Firefox install directory (requires Mozilla Maintenance Service) Support for H.264 on Linux if the appropriate gstreamer plug-ins are installed Support for MP3 decoding on Windows XP, completing MP3 support across Windows OS versions CSP implementation now supports multiple policies, including the case of both an enforced and Report-Only policy, per the specification Social API now supports Social Bookmarking for multiple providers through its SocialMarks functionality Math.ToFloat32 takes a JavaScript value and converts it to a Float32, whenever possible There is no longer a prompt when websites use appcache Support for the CSS image orientation property New App Manager allows you to deploy and debug HTML5 webapps on Firefox OS phones and the Firefox OS Simulator IndexedDB can now be used as a "optimistic" storage area so it doesn't require any prompts and data is stored in a pool with LRU eviction policy, in short temporary storage Fixed: When displaying a standalone image, Firefox matches the Exif orientation information contained within the JPEG image Fixed: Text Rendering Issues on Windows 7 with Platform Update KB2670838 (MSIE 10 Prerequisite) or on Windows 8.1 Improved page load times due to no longer decoding images that are not visible Fixed: AudioToolbox MP3 backend for OS X Various security fixes[350]
26.0.1	December 20, 2013		Fixed the screen that distorts on some devices after tapping on search suggestion. Fixed: About:home is missing translations in some locales. Most affected are: ca, ga-IE, hu, ko, pt-BR, pt-PT, ro, and uk Fixed: In some cases, the clip set on the page doesn't update when the addressbar hides Fixed: Invalid position:fixed rendering[351]
27.0	February 4, 2014	27.0	You can now run more than one service at a time with Firefox SocialAPI, allowing you to receive notifications, chat and more from multiple integrated services Enabled TLS 1.1 (RFC 4346) and TLS 1.2 (RFC 5246) by default Added support for SPDY 3.1 protocol Ability to reset style sheets using 'all:unset' You can now choose to deobfuscate javascript in the debugger Added support for scrolled fieldsets Implemented allow-popups directive for iframe sandbox, enabling increased security CSS cursor keywords -moz-grab and -moz-grabbing have been unprefixed Added support for ES6 generators in SpiderMonkey Implemented support for mathematical function Math.hypot() in ES6 Dashed line support on Canvas Had Azure/Skia content rendering working on Linux Security fixes[141]
27.0.1	February 13, 2014		Fixed stability issues with Greasemonkey and other JavaScript that used ClearTimeoutOrInterval Fixed: JavaScript math correctness issue (bug #941381)[142]
28.0	March 18, 2014	28.0	VP9 video decoding implemented Mac OS X: Notification Center support for web notifications Volume control for HTML5 audio/video Support for Opus in WebM Now that SPDY/3 is implemented support for SPDY/2 has been removed and servers without SPDY/3 will negotiate to HTTP/1 without any penalty Support for MathML 2.0 'mathvariant' attribute Background thread hang reporting Support for multi-line flexbox in layout Security fixes[143]
28.0.1	March 24, 2014		Fixed: No H.264 video playback on several Galaxy devices Fixed: Mobile-only security fix for "file:paths"[145]
29.0	April 29, 2014	29.0	Significant new customization mode A new menu sits in the right hand corner of Firefox and includes popular browser controls New tabs provide an overall smoother look and fade into the background when not active An interactive onboarding tour to guide users through the new Firefox changes Added the ability to set up Firefox Sync by creating a Firefox account Gamepad API finalized and enabled Malay [ma] locale added Clicking on a W3C Web Notification will switch to the originating tab 'box-sizing' (dropping the -moz- prefix) implemented Console object available in web workers Promises enabled by default SharedWorker enabled by default <input type="number"> implemented and enabled <input type="color"> implemented and enabled Enabled ECMAScript Internationalization API Add-on bar has been removed, content moved to navigation bar[146] No longer possible to move tabs from the top of the browser without an add-on
29.0.1	May 9, 2014		Fixed: An issue with pdf.js printing white pages Fixed: Tabs not visible with dark themes under Windows 8.1 Fixed: Session Restore failed with a corrupted sessionstore.js file Fixed: Seer disabled by default[147]
30.0	June 10, 2014	30.0	Sidebars button in browser chrome enables faster access to social, bookmark, & history sidebars Mac OS X command-E sets find term to selected text Support for GStreamer 1.0 Disallowed calling WebIDL constructors as functions on the web With the exception of those bundled inside an extension or ones that are whitelisted, plugins will no longer be activated by default Fixes to box-shadow and other visual overflow Mute and volume available per window when using WebAudio Background-blend-mode enabled by default Use of line-height allowed for <input type="reset|button|submit"> ES6 array and generator comprehensions implemented Error stack now contains column number Support for alpha option in canvas context options Fixed: Ignored autocomplete="off" when offering to save passwords via the password manager Fixed TypedArrays that don't support new named properties[148]
31.0	July 22, 2014	31.0	Adds the search field to the new tab page mozilla::pkix as default certificate verifier Blocks malware from downloaded files Partial implementation of the OpenType MATH table Support of Prefer:Safe http header for parental control audio/video .ogg and .pdf files handled by Firefox if no application specified (Windows only) Upper Sorbian [hsb] locale added Removal of the CAPS infrastructure for specifying site-specific permissions (via capability.policy.* preferences). Most notably, attempts to use this functionality to grant access to the clipboard will no longer work. The sole exception is the checkloaduri permission, which may still be used as before to allow sites to load file:// URIs. WebVTT implemented and enabled CSS3 variables implemented Developer Tools: Add-on Debugger Developer Tools: Canvas Debugger New Array built-in: Array.prototype.fill() New Object built-in: Object.setPrototypeOf() CSP 1.1 nonce-source and hash-source enabled by default Developer Tools: Eyedropper tool added to the color picker Developer Tools: Editable Box Model Developer Tools: Code Editor improvements Developer Tools: Console stack traces Developer Tools: Copy as cURL Developer Tools: Styled console logs navigator.sendBeacon enabled by default Dialogs spawned from the onbeforeunload event no longer block access to the rest of the browser Fixed: Search for partially selected link text from context menu[150]
31.1.0esr	September 2, 2014		Security fix[352]
31.1.1esr	September 24, 2014		Various security fixes[353]
31.2.0esr	October 14, 2014		Security fix Fixed: Invalid certificate issue with mozilla::pkix Fixed: Importing an RSA private key fails if p < q[354]
31.3.0esr	December 1, 2014		Security fix Fixed: @ JS::Handle::operator JSObject* const&() startup crash Fixed: Intermittent failures in add-ons manager mochitest-browser tests Fixed: Bad CPU type in executable running mochitests on yosemite Fixed: Error building nsChildView.mm on OS X 10.10 Fixed: Wrong CPU features detection on some x86 CPUs Fixed: Build error on Yosemite Fixed: XMLHttpRequest.send({}) should not throw[355]
31.4.0esr	January 13, 2015		Security fix[356]
31.5.0esr	February 24, 2015		Security fix[357]
31.5.2esr	March 20, 2015		Security fix for an issue disclosed at HP Zero Day Initiative's Pwn2Own contest[358]
31.5.3esr	March 21, 2015		Security fix for an issue disclosed at HP Zero Day Initiative's Pwn2Own contest[359]
31.6.0esr	March 31, 2015		Security fix[360]
31.7.0esr	May 12, 2015		Security fix[361]
31.8.0esr	July 2, 2015		Security fix[362]
32.0	September 2, 2014	32.0	New HTTP cache provides improved performance including crash recovery Integration of generational garbage collection Public key pinning support enabled Displays the number of found items in the find toolbar Easier back, forward, reload, and bookmarking through the context menu Views historical use information for logins stored in password manager Lower Sorbian [dsb] locale added Removed and turned off trust bit for some 1024-bit root certificates Performance improvements to Password Manager and Add-on Manager drawFocusIfNeeded enabled by default CSS position:sticky enabled by default mix-blend-mode enabled by default Vibration API updated to latest W3C spec box-decoration-break enabled by default ECMAScript 6 built-in method Array#copyWithin implemented New Array built-in: Array.from() navigator.languages property and languagechange event implemented CSS box-decoration-break replaces -moz-background-inline-policy HiDPI support in Developer Tools UI Inspector button moved to the top left Hidden nodes displayed differently in the markup-view New Web Audio Editor Code completion and inline documentation added to Scratchpad Fixed: Mac OS X: cmd-L does not open a new window when no window is available Fixed Text Rendering Issues on Windows 7 with Platform Update KB2670838 (MSIE 10 Prerequisite) or on Windows 8.1 Various security fixes[153]
32.0.1	September 10, 2014 (Android) September 12, 2014 (desktop)		Fixed link tap selection that was offset on some Android devices.[154] Fixed stability issues for computers with multiple graphics cards Fixed mixed content icon that may be incorrectly displayed instead of lock icon for SSL sites Fixed: WebRTC: setRemoteDescription() silently fails if no success callback is specified[155]
32.0.2	September 18, 2014 (desktop)		Fixed corrupt installations causing Firefox to crash on update[156]
32.0.3	September 24, 2014		Various security fixes[157]
33.0	October 14, 2014	33.0	Windows: OMTC enabled by default OpenH264 support (sandboxed) Improved search experience through the location bar Slimmer and faster JavaScript strings Search suggestions on the Firefox Start (about:home) and new tab (about:newtab) pages New CSP (Content Security Policy) backend Support for connecting to HTTP proxy over HTTPS Improved reliability of the session restoration Azerbaijani [az] locale added Proprietary window.crypto properties/functions removed JSD (JavaScript Debugger Service) removed in favor of the Debugger interface @counter-style rule from CSS3 Counter Styles specification implemented DOMMatrix interface implemented Cubic-bezier curves editor Displayed which elements have listeners attached New sidebar which displays a list of shortcuts to every @media rule in the current stylesheet Paint flashing for browser content repaints Editable @keyframes rules in the Rules section of the Inspector CSS transform highlighter in the style-inspector Fixed incomplete downloads being marked as complete by detecting broken HTTP1.1 transfers[160]
33.0.1	October 24, 2014 (desktop)		Fixed: Firefox displays a black screen at startup with certain graphics drivers[161]
33.0.2	October 28, 2014 (desktop)		Fixed a startup crash with some combination of hardware and drivers[162]
33.0.3	November 6, 2014 (desktop)		Blacklisted graphics drivers that were causing black screens with OMTC enabled Fixed two startup crashes with some combination of hardware and drivers[163]
33.1	November 10, 2014 (Firefox's 10-year anniversary[165])		Forget button added Enhanced tiles Privacy tour introduced Adding DuckDuckGo as a search option[164]
33.1.1	November 14, 2014 (desktop)		Fixed a startup crash[166]
34.0	December 1, 2014	34.0	Default search engine changed to Yandex for Belarusian, Kazakh, and Russian locales Improved search bar (en-US only) Firefox Hello real-time communication client Easily switch themes/personas directly in the Customizing mode Wikipedia search now uses HTTPS for secure searching (en-US only) Implementation of HTTP/2 (draft14) and ALPN Recover from a locked Firefox process in the "Firefox is already running" dialog on Windows Disabled SSLv3 Proprietary window.crypto properties/functions re-enabled (to be removed in Firefox 35) Firefox signed by Apple OS X version 2 signature ECMAScript 6 WeakSet Implemented JavaScript Template Strings Implemented CSS3 Font variants and features control (e.g. kerning) implemented WebCrypto: RSA-OAEP, PBKDF2 and AES-KW support WebCrypto: wrapKey and unwrapKey implemented WebCrypto: Import/export of JWK-formatted keys matches() DOM API implemented (formerly mozMatchesSelector()) Performance.now() for workers implemented WebCrypto: ECDH support WebIDE: Create, edit, and test a new Web application from your browser Highlight all nodes that match a given selector in the Style Editor and the Inspector's Rules panel Improved User Interface of the Profiler console.table function added to web console Fixed: CSS transitions start correctly when started at the same time as changes to display, position, overflow, and similar properties Various security fixes[167]
34.0.5	December 1, 2014 (desktop)		Default search engine changed to Yahoo! for North America.[168]
35.0	January 13, 2015	35.0	Firefox Hello with new rooms-based conversations model New search UI improved and enabled for more locales Access the Firefox Marketplace from the Tools menu and optional toolbar button Built-in support for H264 (MP4) on Mac OS X Snow Leopard (10.6) and newer through native APIs Use of tiled rendering on OS X Improved high quality image resizing performance Improved handling of dynamic styling changes to increase responsiveness Implemented HTTP Public Key Pinning Extension (for enhanced authentication of encrypted connections) Added support for the CSS Font Loading API Resource Timing API implemented CSS filters enabled by default Changed JavaScript 'let' semantics to match the ES6 specification Support for inspecting ::before and ::after pseudo elements Computed view: Nodes matching the hovered selector are now highlighted Network Monitor: New request/response headers view Added support for the EXT_blend_minmax WebGL extension Fixed: Show DOM Properties context menu item in inspector Reduced resource usage for scaled images PDF.js updated to version 1.0.907 Non-HTTP(S) XHR now returns correct status code Various security fixes[169]
35.0.1	January 26, 2015 (desktop) February 5, 2015 (Android)		Fixed a crash with the Enhanced Steam extension Fixed a potential startup crash Fixed Kerberos authentication failure with alias Fixed SVG / CSS animation regression causing rendering issues on websites like openstreetmap.org Fixed a crash on Godaddy webmail Fixed an update failure of document.baseURI to document.location after base tag was removed from DOM for site with a CSP Fixed a text selection broken with a Right-to-left (RTL) version of Firefox CSP had a change in behavior with regard to case sensitivity resources loading[170] Fixed crash with video playback on Asus MeMO Pad 10 and 8, Tesco Hudl, Lenovo Lifetab E models, and several other devices running the Rockchip SoC[171]
36.0	February 24, 2015 (desktop) February 27, 2015 (Android)	36.0	Pinned tiles on the new tab page can be synced Added full support for HTTP/2 Locale added: Uzbek (UZ) Remote option removed No longer accepting insecure RC4 ciphers whenever possible Phasing out Certificates with 1024-bit RSA Keys Shut down hangs will now show the crash reporter before exiting the program Add-on compatibility changed Support for the ECMAScript 6 Symbol data type added Unicode-range CSS descriptor implemented CSSOM-View scroll behavior implemented allowing smooth scrolling of content without custom libraries Object-fit and object-position implemented. Isolation CSS property implemented. CSS3 will-change property implemented. Changed JavaScript 'const' semantics to conform better to the ES6 specification. Improved ES6 generators for better performance Eval sources now appear in the Debugger DOM Promises inspection Inspector: More paste options in markup view CSS gradients work on premultiplied colors Fixed some unexpected logout from Facebook or Google after restart Various security fixes[172]
36.0.1	March 5, 2015 (desktop) March 6, 2015 (Android)		Disabled the usage of the ANY DNS query type Fixed a startup crash with EMET Fixed the Hello contact that may become inactive until restart Fixed print preferences that may not be preserved Fixed Hello contact tabs that may not be visible Accepted hostnames that include an underscore character ("_") Fixed the WebGL that may use significant memory with Canvas2d Option -remote has been restored Fixed a top crash[174]
36.0.2	March 16, 2015 (Android)		Fixed a startup crash on HTC One M8 devices (Verizon) with Android 5.0.1 Fixed some potential crashes with Flash videos[176]
36.0.3	March 20, 2015		Security fix for an issue disclosed at HP Zero Day Initiative's Pwn2Own contest[177][178]
36.0.4	March 21, 2015		Security fix for an issue disclosed at HP Zero Day Initiative's Pwn2Own contest[179][180]
37.0	March 31, 2015	37.0	Heartbeat user rating system - your feedback about Firefox Yandex set as default search provider for the Turkish locale Bing search now uses HTTPS for secure searching Improved protection against site impersonation via OneCRL centralized certificate revocation Opportunistically encrypts HTTP traffic where the server supports HTTP/2 AltSvc Disabled insecure TLS version fallback for site security Extended SSL error reporting for reporting non-certificate errors TLS False Start optimization now requires a cipher suite using AEAD construction Improved certificate and TLS communication security by removing support for DSA Improved performance of WebGL rendering on Windows Implemented a subset of the Media Source Extensions (MSE) API to allow native HTML5 playback on YouTube Added support for CSS display:contents IndexedDB now accessible from worker threads New SDP/JSEP implementation in WebRTC Debug tabs opened in Chrome Desktop, Chrome for Android, and Safari for iOS New Inspector animations panel to control element animations New Security Panel included in Network Panel Debugger panel support for chrome:// and about:// URIs Added logging of weak ciphers to the web console[181]
37.0.1	April 3, 2015		Disabled HTTP/2 AltSvc Fixed start-up crash due to graphics hardware and third party software (desktop) Fixed crash due to WebRTC usage on certain web sites (Android) Various security fixes[182][183]
37.0.2	April 14, 2015 (Android) April 20, 2015 (desktop)		Android Fixed an issue related to the "request desktop site" feature[184] Desktop Fixed an issue with Google Maps rendering incorrectly in some cases Fixed stability issues for some graphics hardware and feature sets Security fixes[185]
38.0	May 12, 2015	38.0	New tab-based preferences Ruby annotation support Base for the next ESR release. autocomplete=off is no longer supported for username/password fields URL parser avoids doing percent encoding when setting the Fragment part of the URL, and percent decoding when getting the Fragment in line with the URL spec RegExp.prototype.source now returns "(?:)" instead of the empty string for empty regular expressions Improved page load times via speculative connection warmup WebSocket now available in web workers BroadcastChannel API implemented Implemented srcset attribute and <picture> element for responsive images Implemented DOM3 Events KeyboardEvent.code Mac OS X: Implemented a subset of the Media Source Extensions (MSE) API to allow native HTML5 playback on YouTube Implemented Encrypted Media Extensions (EME) API to support encrypted HTML5 video/audio playback (Windows Vista or later only) Automatically downloaded Adobe Primetime Content Decryption Module (CDM) for DRM playback through EME (Windows Vista or later only) Optimized-out variables are now visible in Debugger UI XMLHttpRequest logs in the web console are now visually labelled and can be filtered separately from regular network requests WebRTC now has multistream and renegotiation support copy command added to console Various security fixes[186]
38.0.1	May 14, 2015 (desktop) May 15, 2015 (Android)		Desktop Fixed a crash on start-up with first generation NVidia Optimus graphics cards Fixed a problem in which users who import cookies from Google Chrome can end up with broken websites Fixed a problem that large animated images may fail to play and may stop other images from loading Fixed a problem that WebRTC H264 video streams from CiscoSpark native clients are not decoded correctly (Fixed in Firefox ESR 38.0.1; was already fixed in Firefox 38.0)[187] Android Fixed a crash on start-up on devices for which Firefox does not support Android hardware acceleration Fixed a problem that large animated images may fail to play and may stop other images from loading Fixed a problem that Mozilla Location Service (MLS) stumbler may not submit all data[188]
38.0.5	June 2, 2015		Desktop Integration of Pocket Implementation of Reader View Share the active tab or window in a Hello conversation Fixed a problem that would cause Firefox to stop painting when switching tabs Fixed graphics performance when using the built-in VGA driver on Windows 7[189] Android Integrated Adjust SDK to measure aggregate installs Fixed various stability fixes[190]
38.1.0esr	July 2, 2015		Security fix[363]
38.1.1esr	August 6, 2015		Critical security fix for an exploit reportedly found in the wild[364]
38.2.0esr	August 11, 2015		Fixed: Firefox may become unresponsive after right-clicking Flash content on Windows 8 Various security fixes Fixed: Firefox may crash during mp4 video playback Fixed branded Firefox application that does not open URLs in system default browser Fixed significant memory leak with GreaseMonkey add-on Fixed crash [@ RtlEnterCriticalSection | MessageLoop::PostTask_Helper] on browser shutdown Fixed browser UI that becomes unresponsive state when using Unity Web Player Plugin Fixed ESRs that would not build on hppa platform Fixed crash in mozilla::layers::SyncObjectD3D11::FinalizeFrame()[365]
38.2.1esr	August 27, 2015		Various security fixes[366]
38.3.0esr	September 22, 2015		Various security fixes[367]
38.4.0esr	November 3, 2015		Various security fixes[368]
38.5.0esr	December 15, 2015		Various security fixes[369]
38.5.1esr	December 21, 2015		Preparing to use SHA-256 signing certificate for Windows builds, to meet new signing requirement[370]
38.5.2esr	December 22, 2015		Various stability and security fixes Use of a SHA-256 signing certificate for Windows builds, to meet new signing requirements[371]
38.6.0esr	January 26, 2016		Various security fixes[372]
38.6.1esr	February 11, 2016		Updated graphite2 library to latest release[373]
38.7.0esr	March 8, 2016		Various security fixes[374]
38.7.1esr	March 16, 2016		Fixed an issue in which loading from history can show the wrong url in the location bar Disabled Graphite font shaping library[375]
38.8.0esr	April 26, 2016		Various security fixes[376]
39.0	July 2, 2015	39.0	Share Hello URLs with social networks Project Silk: Smoother animation and scrolling (Mac OS X) Support for 'switch' role in ARIA 1.1 (web accessibility) SafeBrowsing malware detection lookups enabled for downloads (Mac OS X and Linux) Support for new Unicode 8.0 skin tone emoji Removed support for insecure SSLv3 for network communications Disable use of RC4 except for temporarily whitelisted hosts The malware detection service for downloads now covers common Mac file types (Bug 1138721) Performance of displaying dashed lines is improved (Mac OS X) (Bug 1123019) List-style-type now accepts a string value Enable the Fetch API for network requests from dedicated, shared and service workers Cascading of CSS transitions and animations now matches the current spec Implement <link rel="preconnect">allowing anticipation of a future connection without revealing any information Added support for CSS Scroll Snap Points Drag and drop enabled for nodes in Inspector markup view Webconsole input history persists even after closing the toolbox Cubic bezier tooltip now shows a gallery of timing-function presets for use with CSS animations localhost is now available offline for WebSocket connections Improve performance for IPv6 fallback to IPv4 Fixed incomplete downloads being marked as complete by detecting broken HTTP1.1 transfers Fixed the security state indicator on a page now correctly ignores loads caused by previous pages Fixed an issue where a Hello conversation window would sometimes fail to open Fixed a regression that could lead to Flash not displaying has been fixed Update to NSS 3.19.2 Various security fixes[192]
39.0.3	August 6, 2015		Critical security fix for an exploit reportedly found in the wild[193][364]
40.0	August 11, 2015	40.0	Support for Windows 10 Added protection against unwanted software downloads User can receive suggested tiles in the new tab page based on categories Firefox matches to browsing history (en-US only). Hello allows adding a link to conversations to provide context on what the conversation will be about New style for add-on manager based on the in-content preferences style Improved scrolling, graphics, and video playback performance with off-main-thread compositing (Linux only) Graphic blocklist mechanism improved: Firefox version ranges can be specified, limiting the number of devices blocked Add-on extensions that are not signed by Mozilla will display a warning NPAPI Plug-in performance improved via asynchronous initialization Smoother animation and scrolling with hardware vsync (Windows only) JPEG images use less memory when scaled and can be painted faster Sub-resources can no longer request HTTP authentication, thus protecting users from inadvertently disclosing login data IndexedDB transactions are now non-durable by default Implemented AudioBufferSourceNode.detune to modulate playback rate in cents, a logarithmic unit of measure used for musical intervals Improved Performance tools in the developer tools: Waterfall view, Call Tree view and a Flame Chart view New rules view tooltip in the Inspector to tweak CSS Filter values Console API messages from SharedWorker and ServiceWorker are now displayed in web console New page ruler highlighting tool that displays lightweight horizontal and vertical rules on a page Inspector now searches across all content frames in a page Fixed Kannada text that does not display properly in built-in pdf viewer Various security fixes[195]
40.0.2	August 13, 2015		Enabled API allowing Windows 10 users to open settings dialog Fixed mozalloc.lib that was missing from the xulrunner package Fixed a startup crash with some combination of hardware and drivers[197]
40.0.3	August 27, 2015		Disabled the asynchronous plugin initialization Fixed a segmentation fault in the GStreamer support (Linux only) Fixed a startup crash when using DisplayLink (Windows only) Fixed a regression with some Japanese fonts used in the <input> field Fixed an issue that the selection in a select combox box using the mouse could be broken on some sites Fixed an issue that some search partner codes were missing Various security fixes[198]
41.0	September 22, 2015	41.0	Enhanced IME support on Windows (Vista +) using TSF (Text Services Framework) Ability to set a profile picture for your Firefox Account Firefox Hello now includes instant messaging SVG images can be used as favicons Improved box-shadow rendering performance WebRTC now requires perfect forward secrecy WARP is disabled on Windows 7 Updates to image decoding process Support for running animations of 'transform' and 'opacity' on the compositor thread MessageChannel and MessagePort API enabled by default Added support for the transform-origin property on SVG elements CSS Font Loading API enabled by default Navigator.onLine now varies with actual internet connectivity (Windows and Mac OS X only) Copy/Cut Web content from JavaScript to the OS clipboard with document.execCommand("cut"/"copy") Implemented Cache API for querying named caches that are accessible Window, Worker, and ServiceWorker Removed support for binary XPCOM components in extensions, use addon SDK "system/child_process" pipe mechanism for native binaries instead Network requests can be exported in HAR format Quickly adds new CSS rule with New Rule button in the Inspector Screenshots a node or element from markup view with the Screenshot Node context menu item Copies element CSS rule declarations with the Copy Rule Declaration context menu item in the Inspector Pseudo-Class panel in the Inspector Fixed an issue where picture element does not react to resize/viewport changes Various security fixes[200]
41.0.1	September 30, 2015 (desktop)		Fixed a startup crash related to Yandex toolbar and Adblock Plus Fixed potential hangs with Flash plugins Fixed a regression in the bookmark creation Fixed a startup crash with some Intel Media Accelerator 3150 graphic cards Fixed a graphic crash, occurring occasionally on Facebook[202]
41.0.2	October 15, 2015		Various security fixes.[203]
42.0	November 3, 2015	42.0	Private Browsing with Tracking Protection that blocks certain Web elements that could be used to record your behavior across sites Control Center that contains site security and privacy controls Indicator added to tabs that play audio with one-click muting WebRTC improvements: IPV6 support Preferences for controlling ICE candidate generation and IP exposure Hooks for extensions to allow/deny createOffer/Answer Improved ability for applications to monitor and control which devices are used in getUserMedia Login Manager improvements: Improved heuristics to save usernames and passwords Editing and showing all logins in line, Copy/Paste usernames/passwords from the Context menu Migration imports your passwords to Firefox from Google Chrome for Windows and Internet Explorer; import anytime from the Login Manager Improved performance on interactive websites that trigger a lot of restyles Implemented ES6 Reflect Support for ImageBitmap and createImageBitmap() Media Source Extension for HTML5 video available for all sites Viewing HTML source in a tab Remote website debugging over WiFi (no USB cable or ADB needed) Asynchronous call stacks now allow web developers to follow the code flow through setTimeout, DOM event handlers, and Promise handlers Configurable Firefox OS Simulator in WebIDE, to simulate reference devices like phones, tablets, even TVs CSS filter presets in the Inspector Ability to save filter presets inside CSS Filter Tooltip[204]
43.0	December 15, 2015	43.0	Private Browsing with Tracking Protection offers choice of blocking additional trackers Improved API support for m4v video playback Firefox 64-bit for Windows is now available via the Firefox download page Users can choose search suggestions from the Awesome Bar On-screen keyboard displayed on selecting input field on devices running Windows 8 or greater Firefox Health Report has switched to use the same data collection mechanism as telemetry Markup view shows indicators for pseudo-classes locked for elements Binding F1 key to open the settings when the toolbox is focused New 'Use in Console' context menu item in Inspector to store selected element in a temporary variable Search button next to overridden CSS properties to find similar properties in the rules view Ability to filter styles from their property names in the rules view Stack traces are now shown for exceptions inside the console Added ability to display server-side logs in the console Ability to choose resolution for the GCLI screenshot command Subresource integrity allows developers to make their sites more secure Network requests in Console now link to Network panel instead of opening in a popup Unprefixed 'hyphens' property is now supported WebIDE now has a sidebar-based UI The 'transform-origin' property is now supported on SVG elements Animation inspector now displays animations in a timeline Single-process mode is no longer supported for NPAPI plugins Fixed an issue in which the Eyedropper tool does not work as expected when page is zoomed Various security fixes[206]
43.0.1	December 18, 2015 (desktop)		Preparing to use SHA-256 signing certificate for Windows builds, to meet new signing requirement[208]
43.0.2	December 22, 2015 (desktop)		Various stability and security fixes Use of a SHA-256 signing certificate for Windows builds, to meet new signing requirements[209]
43.0.3	December 28, 2015 (desktop)		Fixed network issue when using Nvidia's Network Access Manager On some Windows configurations, improved the decoding of some videos on YouTube[210]
43.0.4	January 6, 2016 (desktop)		Fix for startup crash for users of a third party antivirus tool Multi-user GNU/Linux download folders can be created Re-enabled SHA-1 certificates[211]
44.0	January 26, 2016	44.0	Improved warning pages for certificate errors and untrusted connections Enabled H.264 if system decoder is available Enabled WebM/VP9 video support on systems that don't support MP4/H.264 In the animation-inspector timeline, lightning bolt icon next to animations running on the compositor thread Support for the brotli compression format via HTTPS content-encoding Screenshot commands allow user choice of pixel ratio in Developer Tools Fixed an issue where Windows XP and Vista screensaver doesn't disable when watching videos Various security fixes To support unicode-range descriptor for webfonts, font matching under Linux now uses the same font matching code as other platforms Use of a SHA-256 signing certificate for Windows builds, to meet new signing requirements Firefox has removed support for the RC4 decipher Firefox will no longer trust the Equifax Secure Certificate Authority 1024-bit root certificate or the UTN - DATACorp SGC to validate secure website certificates Stricter validation of web fonts On-screen keyboard support temporarily turned off for Windows 8 and Windows 8.1 Right-clicking on a logged object in the console to store it as a global variable on the page Visual tools for Animation: View/Edit CSS animation keyframe rules directly in the inspector Visually modify the cubic-bezier curve that drives the way animations progress through time Discover and scrub through all CSS animations and transitions playing on the page Learn more: http://devtoolschallenger.com/ Visual tools for Layout and Styles: Display rulers along the viewport to verify size and position and use the measurement tool to easily detect spacing and alignment problems Use CSS filters to preview and create real-time effects like drop-shadows, sepia, etc. Learn more: http://devtoolschallenger.com/ New memory tool for inspecting the memory heap Service Workers API Built-in JSON reader to intuitively view, search, copy and save data without extensions A jump to function definitions in the debugger with Cmd-Click WebSocket Debugging API and add-on The rule view now displays styles using their authored text, and edits in the rule view are now linked to the style editor[212]
44.0.1	February 8, 2016 (desktop)		Fixed an issue which could lead to the removal of stored passwords under certain circumstances Allows spaces in cookie names Requires NSS 3.21 Fixed a crash in cache networking Fix for using WebSockets in service worker controlled pages Disabled opus/vorbis audio with H.264 Shipment for the Gecko SDK Fix for graphics startup crash (GNU/Linux)[215]
44.0.2	February 11, 2016		Fixed an issue where Firefox hangs or crashes on startup Various security fixes[216]
45.0	March 8, 2016	45.0	Instant browser tab sharing through Hello Tabs synced via Firefox Accounts from other devices are now shown in dropdown area of Awesome Bar when searching Synced Tabs button in button bar Introduces a new preference (network.dns.blockDotOnion) to allow blocking .onion at the DNS level Guarani [gn] locale added URLs containing a Unicode-format Internationalized Domain Name (IDN) are now properly redirected Various security fixes Tab Groups (Panorama) feature removed Ability to filter snapshot output in memory tool Fine-tuning animations by changing the playback rate of animations in the animation-inspector's timeline DOMContentLoaded and load events shown in the network monitor timeline Added Negative url filtering for the network monitor Support for diffing heap snapshots added to the memory tool Inspector search now matches results from all content in the page, including subframes List of animated properties and keyframes is now displayed when clicking on an animation in the animation-inspector’s timeline Push API support, part of Progressive Web Applications Support for delivery of a Content Security Policy (CSP) via a meta tag Web Speech synthesis API ES6 Classes[218]
45.0.1	March 16, 2016		Fix for a potential performance regression (YouTube for example) Fix for a regression causing search engine settings to be lost in some context Brings back non-standard jar: URIs to fix a regression in IBM iNotes Fixed an issue in which XSLTProcessor.importStylesheet was failing when <import> was used Fix for an issue which could cause the list of search provider to be empty Fix for a regression when using the location bar Fix for some loading issues when Accept third-party cookies: was set to Never Disabled Graphite font shaping library[220]
45.0.2	April 11, 2016		Fix for an issue impacting the cookie header when third-party cookies are blocked Fix for a web compatibility regression impacting the srcset attribute of the image tag Fix for a regression with the copy and paste with some old versions of some Gecko applications like Thunderbird (desktop only) Fix for a crash impacting the video playback with Media Source Extension Fix for a regression impacting some specific uploads[222]
45.1.0esr	April 26, 2016		Various security and stability fixes.[377]
45.1.1esr	May 3, 2016		Fixed a build issue when jit is disabled Fixed add-on signing certificate expiration Fixed a graphics-related shutdown crash[378]
45.2.0esr	June 7, 2016		Fixed graphics-related crashes Various security fixes Fixed unicode support for AutoConfig API Web compatibility fix for addEventListener API[379]
45.3.0esr	August 2, 2016		Various stability fixes Various security fixes[380]
45.4.0esr	September 20, 2016		Various security fixes[381]
45.5.0esr	November 15, 2016		Various security fixes[382]
45.5.1esr	November 30, 2016		Various security fixes[383]
46.0	April 26, 2016	46.0	Improved security of the JavaScript Just In Time (JIT) Compiler GTK3 integration (GNU/Linux only) Screen reader behavior with blank spaces in Google Docs corrected Corrected rendering for scaled SVGs that use a clip and a mask WebRTC fixes to improve performance and stability Display of dominator trees in Memory tool Allocation and garbage collection pause profiling in the performance panel Launch of responsive mode from the Style Editor @media sidebar Added support for document.elementsFromPoint Added HKDF support for Web Crypto API[224]
46.0.1	May 3, 2016		Fixed add-on signing certificate expiration Fixed service worker update issue Fixed a build issue when jit is disabled Fixed a page loading issue related to antivirus software Searched a plugin issue for various locales Limited Sync registration updates[226]
47.0	June 7, 2016	47.0	Support for Google’s Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video. Enabled VP9 video codec for users with fast machines Embedded YouTube videos now play with HTML5 video if Flash is not installed. Ability to view and search open tabs from your smartphone or another computer in a sidebar Allowed no-cache on back/forward navigations for https resources Latgalu [ltg] locale added. Various security fixes FUEL (Firefox User Extension Library) has been removed. Add-ons relying on it will stop working. The browser.sessionstore.restore_on_demand preference has been reset to its default value (true) to avoid e10s performance problems. The Firefox click-to-activate plugin whitelist has been removed. Web platform changes Ability to view, start, and debug registered Service Workers in the Service Workers developer tool Ability to simulate Push messages in the Service Workers developer tool 'Start' button for service workers in about:debugging to start registered Service Workers Changes that can affect add-on compatibility Added support for ChaCha20/Poly1305 cipher suites Custom user agents supported in Responsive Design Mode Smart multi-line input in the Web Console cuechange events are now available on TextTrack objects WebCrypto: PBKDF2 supports SHA-2 hash algorithms WebCrypto: RSA-PSS signature support[228] Last release to support Android 2.3.x (Gingerbread)[229]
47.0.1	June 28, 2016 (desktop)		Fixed an issue in which Selenium WebDriver may cause Firefox to crash at startup[230]
48.0	August 2, 2016	48.0	Roar for moar protection against harmful downloads! We've got your back Process separation (e10s) is enabled for some of you. Like it? Let us know and we'll roll it out to more. Add-ons that have not been verified and signed by Mozilla will not load GNU/Linux fans: Get better Canvas performance with speedy Skia support. Try saying that three times fast WebRTC embetterments: Delay-agnostic AEC enabled Full duplex for GNU/Linux enabled ICE Restart & Update is supported Cloning of MediaStream and MediaStreamTrack is now supported Searching for something already in your bookmarks or open tabs? We added super smart icons to let you know Windows folks: Tab (move buttons) and Shift+F10 (pop-up menus) now behave as they should in Firefox customization mode The media parser has been redeveloped using the Rust programming language Various security fixes Heyo, Jabra & Logitech C920 webcam users. We fixed those pesky WebRTC bugs causing frequency distortions. Buh-bye, squeaky voice! Improved step debugging on last line of functions After version 48, SSE2 CPU extensions are going to be required on Windows So long to support for 10.6, 10.7 and 10.8. Now we can focus on where most Mac users are: 10.9. Don't forget to upgrade! Au revoir to Windows Remote Access Service modem Autodial WebExtensions support is now considered as stable Want to move absolute & fixed positioned elements? (Who doesn't, right?) Now you can with our geometry editor. The memory tool now has a tree map view for your debugging pleasure. It's a little bit of "boo" and a whole lot of "ya." We're putting the spotlight on the background. Now you can debug WebExtensions background content scripts and background pages Content Security Policy (CSP) is now enforced for WebExtensions. (Who's down with CSP?) Old and busted: Error Console. New hotness: Browser Console for your debugging pleasure. Add-on development just got easier because you can reload them from about:debugging — because we're all about debugging. This theme is hot, hot, hot! Say hi to the Firebug theme for Developer Tools. Expanded network requests from the console panel to view request details in line, so you can see things in context Workers can now use the Web Crypto API[231]
48.0.1	August 18, 2016 (desktop)		Fix for an audio regression impacting some major websites Fix for a top crash in the JavaScript engine Fix for a startup crash issue caused by Websense Fix for a different behavior with e10s / non-e10s on <select> and mouse events Fix for a top crash caused by plugin issues Fix for an unsigned add-ons issue on Windows Fix for a shutdown issue Fix for a crash in WebRTC[233]
48.0.2	August 24, 2016 (desktop)		Fix for a startup crash issue caused by Websense (Windows only)[234]
49.0	September 20, 2016	49.0	Updated Firefox Login Manager to allow HTTPS pages to use saved HTTP logins. It’s one more way Firefox is supporting Let’s Encrypt and helping users transition to a more secure web. Added features to Reader Mode that make it easier on the eyes and the ears Controls that allow users to adjust the width and line spacing of text Narrate, which reads the content of a page out loud Improved video performance for users on systems that support SSSE3 without hardware acceleration Added context menu controls to HTML5 audio and video that let users loops files or play files at 1.25x speed Enhancements for Mac users Improved performance on OS X systems without hardware acceleration Improved appearance of anti-aliased OS X fonts Improvements in about:memory reports for tracking font memory usage Improved performance on Windows systems without hardware acceleration Fixed an issue that prevented users from updating Firefox for Mac unless they originally installed Firefox. Now, those users as well as any user with administrative credentials can update Firefox. Various security fixes Ended Firefox for Mac support for OS X 10.6, 10.7, and 10.8. Ended Firefox for Windows support for SSE processors Removed Firefox Hello Re-enabled the default for Graphite2 font shaping Added a Cause column to the Network Monitor to show what caused each network request Introduced web speech synthesis API[235]
49.0.1	September 23, 2016 (desktop)		Mitigated a startup crash issue caused by Websense (Windows only)[237]
49.0.2	October 20, 2016		Asynchronous rendering of the Flash plugins is now enabled by default. This should improve performance and reduce crashes for sites that use the Flash plugin. Changed D3D9 default fallback preference to prevent graphical artifacts Fixed a network issue that prevents some users from seeing the Firefox UI on startup Fixed a web compatibility issue with Array.prototype.values Various security fixes Fixed a web compatibility issue with file uploads Diagnostic information on timing for tab switching Fix for a Canvas filters graphics issue affecting HTML5 apps[238]
50.0	November 15, 2016	50.0	Playback video on more sites without plugins with WebM EME Support for Widevine on Windows and Mac Improved performance for SDK extensions or extensions using the SDK module loader Added download protection for a large number of executable file types on Windows, Mac and Linux Increased availability of WebGL to more than 98 percent of users on Windows 7 and newer Added Guarani (gn) locale Added option to Find in page that allows users to limit search to whole words only Updates to keyboard shortcuts Set for a preference to have Ctrl+Tab cycle through tabs in recently used order View for a page in Reader Mode by using Ctrl+Alt+R (command+alt+r on Mac) Various security fixes Blocked versions of libavcodec older than 54.35.1 Added a built-in Emoji set for operating systems without native Emoji fonts (Windows 8.0 and lower and Linux) Changes for web developers[240] Added support for HLS videos via player overlay (Android) Simplified the user interface by combining the Recent Tabs and History panels (Android)[241]
50.0.1	November 28, 2016 (desktop)		Fixed an issue where Firefox crashes with 3rd party Chinese IME when using IME text Various security fixes[242]
50.0.2	November 30, 2016		Various security fixes[243]

Release compatibility

Operating system		Latest stable version	Support status
Windows	7 and later	50.0.2 (IA-32), 50.0.2 (x64), 45.5.1esr (IA-32) and 45.5.1esr (x64)[384]	2009—
	XP, Server 2003 SP1 and Vista	50.0.2 (IA-32) and 45.5.1esr (IA-32)[384][385]	2004–2018
	2000, XP (RTM, SP1) and Server 2003 RTM	10.0.12esr[386] and 12.0	2004–2013
	NT 4, 98, 98 SE and ME	2.0.0.20	2004–2008
	95	1.5.0.12	2004–2007
macOS	10.9–10.12	50.0.2 and 45.5.1esr[384]	2013—
	10.6–10.8	45.5.1esr; and 47.0.1 was supported[384][387]	2009–2017
	10.5 (Intel)	10.0.12esr and 16.0.2[388]	2007–2013
	10.4–10.5 (PPC)	3.6.28[389][390]	2005–2012
	10.2–10.3	2.0.0.20	2004–2008
	10.0–10.1	1.0.8	2004–2006
Linux	Desktop	50.0.2 (i686), 50.0.2 (x86_64),[384] 45.5.1esr (i686) and 45.5.1esr (x86_64)	2004—
	Android 4.0 and newer	50.0.2[391]	2011—
	Android 3.0	45.0.2[391]	2011–2016
	Android 2.3	47.0[391][392]	2011–2016
	Android 2.2	31.0[393] and 31.3.0esr	2011–2014
	Android 2.1	19.0.2	2011–2013
	Android 2.0	6.0.2	2011
	Maemo	7.0	2010–2011
	MeeGo	15.0	2011–2014
	Firefox OS 2.2	35/36/37	2015
	Firefox OS 2.0	31/32.0	2013–2015

Notes

• Firefox for iOS is not listed in this table as its version numbers would be misleading (it uses version numbers that do not correspond to any of the other Firefox versions, as those share a core component, the Gecko rendering engine and track its version numbers while the version for the iOS operating system uses the operating system's rendering engine (WebKit), rather than Mozilla's Gecko).
• Green color denotes current Firefox versions, while the red colour is for older versions.
• In March 2014, the Windows Store app version of Firefox was cancelled, although there is a beta release.^[394]

See also

• Firefox release history
• GNU IceCat
• History of free and open-source software
• History of Mozilla Application Suite
• Mozilla Corporation software rebranded by the Debian project

References

Further reading

External links

• Mozilla Firefox release notes for each version
• MozillaZine Weblogs at the Wayback Machine (archived July 17, 2011), Where Did Firefox Come From?
• Releases - MozillaWiki, Releases - MozillaWiki
• BBC News, Firefox browser for web 2.0 age
• Indistinguishable from Jesse, Jesse Ruderman, unofficial changelogs for Firefox releases (last updated in 2008)