# Firefox early version history

The project that became Firefox today began as an experimental branch of the Mozilla Suite called m/b (or mozilla/browser). Firefox retains the cross-platform nature of the original Mozilla browser, using the XUL user interface markup language. The use of XUL made 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.

## Releases
### Phoenix and Firebird

Hyatt, Ross, Hewitt and Chanial 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, news, and WYSIWYG HTML editing into one internet suite. After it was 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 Netscape Navigator which lost the "First browser war" to Microsoft's Internet Explorer. The name Mozilla began as the internal codename for the original 1994 Netscape Navigator browser aiming to displace NCSA Mosaic as the world's most popular web browser. The name for this would-be "Mosaic killer" was meant to evoke the building-crushing Godzilla. The name Mozilla was revived as the 1998 open sourcing spinoff organization from Netscape.
The name Phoenix remained 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.
Release history of Phoenix :
| Version | Codename | Release date | Release type and highlights |
| 0.1 | Pescadero | September 23, 2002 | First release. Gecko version 1.2 Customizable toolbar Quicksearch |
| 0.2 | Santa Cruz | October 1, 2002 | Official version 0.2 release. Web form auto-complete Sidebar Downloads Sidebar Bookmarks Sidebar History Sidebar Extension management Toolbar customization Search bar Improved preference defaults Speed improvements Ctrl+Mousewheel to resize fonts |
| 0.3 | Lucia | October 14, 2002 | Official version 0.3 release. Image Blocking Pop-up Blocking Whitelist Bookmarks Changes Global Go Menu and Other Menu Changes Tabbed Browsing Improvements Size and Speed Improvements |
| 0.4 | Oceano | October 19, 2002 | Official version 0.4 release. Gecko version 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 |
| 0.5 | Naples | December 7, 2002 | Official version 0.5 release. 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 |
Release history of Firebird :
| Version | Codename | Release date | Release type and highlights |
| 0.6 | Glendale | May 17, 2003 | Official version 0.6 release. Gecko version 1.5 New default theme (Qute) 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 |
| 0.6.1 | | July 28, 2003 | Bugfix release. |
| 0.7 | Indio | October 15, 2003 | Technology Preview. First publication on October 26, 2003 Advanced preferences panel Download/helper applets preferences panel Cookie whitelisting New password manager (all passwords now stored encrypted) 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 |
| 0.7.1 | Three Kings | October 26, 2003 | Bugfix release for Mac OS X only. |

### Firefox

Due to continuing pressure from the Firebird community, on February 9, 2004, the project was renamed again to Mozilla Firefox. The name "Firefox" (a reference to the red panda) was chosen for its similarity to "Firebird", and 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 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 for Charlton Company software. The situation was resolved when the foundation was given a license to use Charlton's European trademark.
Firefox version 1.0 was released on November 9, 2004. The launch of version 1.0 was accompanied by "a respectable amount of pre-launch fervor" 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 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.
Pre-release history of Firefox :
| Version | Codename | Release date | Release type and highlights |
| 0.8 | Royal Oak | February 9, 2004 | Technology Preview. Gecko version 1.6 Rebranded with new logo. 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. |
| 0.9 | One Tree Hill | June 15, 2004 | Technology Preview. Gecko version 1.7 New default theme "Winstripe". Comprehensive Data Migration from Internet Explorer. Extension/Theme Manager Online help system Linux installer |
| 0.9.1 | | June 28, 2004 | Bugfix release Updated default theme. |
| 0.9.2 | | July 8, 2004 | Vulnerability patch for Windows only. |
| 0.9.3 | | August 4, 2004 | Vulnerability patch. |
| 0.10 | Greenlane | September 14, 2004 | Bugs with higher complexity/risk, localization impact, RSS/Atom feed support, find toolbar, plugin finder. |
| 0.10.1 | | October 1, 2004 | Vulnerability patch. |
Release history of Firefox 1 :
| Version | Codename | Release date | Release type and highlights |
| 1.0 | Phoenix | November 9, 2004 | Official version 1.0 release. Better Tabbed Browsing Controls Official localized builds |
| 1.0.1 | Rose & Crown | February 24, 2005 | Regular security and stability update. |
| 1.0.2 | | March 23, 2005 | Regular security and stability update. |
| 1.0.3 | | April 15, 2005 | Regular security and stability update. Installer improvements. |
| 1.0.4 | | May 11, 2005 | Regular security and stability update. Fix to DHTML errors encountered at some web sites. |
| 1.0.5 | | July 12, 2005 | Regular security and stability update. |
| 1.0.6 | | July 19, 2005 | Off-cycle stability update. Restored API compatibility for extensions and web applications that did not work in Firefox 1.0.5. |
| 1.0.7 | | September 20, 2005 | Regular security and stability update. |
| 1.0.8 | | April 13, 2006 | Regular security and stability update. End-of-life 1.0.x product line Last release for Mac OS X 10.0–10.1 |

### Firefox 1.5

Firefox 1.5 was released on November 30, 2005. Originally, it was planned to have a version 1.1 at an earlier date as the new Firefox version after 1.0, with development on a later version (1.5) in a separate development branch, but during 2005 both branches and their feature sets were merged (the Mozilla Foundation abandoned the 1.1 release plan after the first two alpha builds), resulting in an official release date between the original dates planned for both versions.
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.
Behind the screens, 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.
There were also changes in operating system support. As announced on 23 June 2005 by the Mozilla Foundation, Firefox 1.1, which later became 1.5, and other new Mozilla products have no longer supported 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 is the final version to support Windows 95.
Alpha builds of Firefox 1.5 (id est, 1.1a1 and 1.1a2) did not carry Firefox branding; they were labelled "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.
Release history of Firefox 1.5 :
| Version | Codename | Release date | Release type and highlights |
| 1.5 | Deer Park | November 29, 2005 | Official version 1.5 release. Official localized builds. Gecko version 1.8 Private data clear data Back and forward now fast Improved web standards Improved HTML Improved CSS Improved HTTP Improved JavaScript/DOM SVG compatibility Changes during alphas Support for SVG and canvas. Sanitize privacy feature. Improvements in JavaScript 1.5 and CSS 2/3. Broken website reporter tool. Blazing fast backwards and forwards (FastBack), drag-and-drop tab reordering, improved pop-up blocking, error pages instead of error dialogs. Changes during betas New update system (binary patch). Prettier error pages, more Luna-like Winstripe theme (did not blend well with the Classic theme). Improvements to automated update system, website rendering and performance. Several security fixes. |
| 1.5.0.1 | | February 1, 2006 | Regular security and stability update. |
| 1.5.0.2 | | April 13, 2006 | Regular security and stability update. Native support for Intel-based Macintosh computers by shipping universal binary. |
| 1.5.0.3 | | May 2, 2006 | Off-cycle security update. Fix for a publicly disclosed denial of service weakness. |
| 1.5.0.4 | | June 1, 2006 | Regular security and stability update. |
| 1.5.0.5 | | July 26, 2006 | Regular security and stability update. Added changes for Frisian locale (fy-NL). |
| 1.5.0.6 | | August 2, 2006 | Off-cycle security and stability update. Fixed an issue with playing Windows Media content introduced by previous update. |
| 1.5.0.7 | | September 14, 2006 | Regular security and stability update. |
| 1.5.0.8 | | November 7, 2006 | Regular security and stability update. |
| 1.5.0.9 | | December 19, 2006 | Regular security and stability update. |
| 1.5.0.10 | | February 23, 2007 | Regular security and stability update. |
| 1.5.0.11 | | March 20, 2007 | Regular security and stability update. Regression fixes. |
| 1.5.0.12 | | May 30, 2007 | Regular security and stability update. End-of-life 1.5.0.x product line Last version to support Windows 95. |

### Firefox 2

On October 24, 2006, Mozilla released Firefox 2. This version included updates to the tabbed browsing environment, the extensions manager, the GUI (graphical user interface), and the find, search and software update engines. It also implemented a new session restore feature, inline spell checking, and an anti-phishing feature which was implemented by Google as an extension and later merged into the program itself.
In December 2007, Firefox Live Chat was launched. It allowed users to ask volunteers questions through a system powered by Jive Software, with guaranteed hours of operation and the possibility of help after hours.
Firefox 2.0.0.20 was the final version that could run under an unmodified installation of Windows NT 4.0, Windows 98, and Windows Me. Subsequently, 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.
Release history of Firefox 2 :
| Version | Codename | Release date | Release type and highlights |
| 2.0 | Bon Echo | October 24, 2006 | Official version 2.0 release. Official localized builds. Gecko version 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 "Changes during alphas" Links default to open in new tab. Close button on every tab. Inline spell checking for text boxes. Session restoration after browser crash. Search suggestion for Google and Yahoo!. New search plugin manager and add-on manager. Web feed previewing. Bookmark microsummaries. Updates to extension system. Support for Sherlock and OpenSearch. Support for SVG text using svg:textPath. Anti-phishing protection. Search suggestions appear with search history in the search box for Google and Yahoo!. Support for client-side session and persistent storage. Changes during betas Improved feed support. New NSIS-based installer. JavaScript 1.7. Enhanced security and localization support for extensions. New Winstripe theme refresh: new navigation icons, URL bar refresh (new Go button attached to the URL bar), Search bar refresh, Tab bar refresh, Alltabs button (used to view a popup list of all tabs open). |
| 2.0.0.1 | | December 19, 2006 | Regular security and stability update. Windows Vista support. |
| 2.0.0.2 | | February 23, 2007 | Regular security and stability update. |
| 2.0.0.3 | | March 20, 2007 | Regular security and stability update. Regression fixes and security fixes. |
| 2.0.0.4 | | May 30, 2007 | Regular security and stability update. |
| 2.0.0.5 | | July 17, 2007 | Security and stability update. |
| 2.0.0.6 | | July 30, 2007 | Regular security and stability update. |
| 2.0.0.7 | | September 18, 2007 | Off-cycle security update. |
| 2.0.0.8 | | October 18, 2007 | Regular security and stability update. Mac OS X 10.5 support. |
| 2.0.0.9 | | November 1, 2007 | Off-cycle security and stability update. |
| 2.0.0.10 | | November 26, 2007 | Off-cycle security and stability update. |
| 2.0.0.11 | | November 30, 2007 | Off-cycle stability update. |
| 2.0.0.12 | | February 7, 2008 | Regular security and stability update. |
| 2.0.0.13 | | March 25, 2008 | Regular security and stability update. |
| 2.0.0.14 | | April 16, 2008 | Off-cycle stability update. |
| 2.0.0.15 | | July 1, 2008 | Regular security and stability update. |
| 2.0.0.16 | | July 15, 2008 | Off-cycle security update. |
| 2.0.0.17 | | September 23, 2008 | Regular security and stability update. |
| 2.0.0.18 | | November 12, 2008 | Regular security and stability update. |
| 2.0.0.19 | | December 16, 2008 | Regular security and stability update. |
| 2.0.0.20 | | December 18, 2008 | Off-cycle security update. Bug fixes Fixed security and stability issues. End-of-life 2.0.0.x product line Last version to support Windows NT 4.0, Windows 98, Windows Me and Mac OS X 10.2–10.3. |

### Firefox 3

Firefox 3 was released on June 17, 2008, 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. Other new features include a redesigned download manager, a new "Places" system for storing bookmarks and history, and separate themes for different operating systems.
Development stretches back to the first Firefox 3 beta (under the codename 'Gran Paradiso') which had been released several months earlier on November 19, 2007, and was followed by several more beta releases in spring 2008 culminating in the June release. Firefox 3 had more than 8 million unique downloads the day it was released, setting a Guinness World Record.
Release history of Firefox 3 :
| Version | Codename | Release date | Release type and highlights |
| 3.0 | Gran Paradiso | June 17, 2008 | Official version 3.0 release. Gecko version 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 parties 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 Changes during alphas Cairo graphics library. Cocoa Widgets in OS X builds. Updated threading model. Changes to how DOM events are dispatched, how HTML object elements are loaded, and how web pages are painted. New SVG elements and filters, and improved SVG specification compliance. Windows 95, 98, ME and Mac OS X v10.2 no longer supported. Moving DOM nodes between documents require a call to importNode or adoptNode as per the DOM specification. Reflow refactoring (leading to Acid2 test compliance) among numerous layout bug fixes. Web Apps 1.0 API for changing stylesheets support. Inline-block and inline-table values of CSS 2.1's display property implemented. XML documents can be rendered during download. Greatly improved Mac widgets support since Alpha 1. Improvements in Cairo graphics layer. Non-standard JavaScript "Script" object no longer supported. Support for allowing web pages to store resources in the browser's offline cache. Support for Animated PNG images. Support for the "HTTPOnly" cookie extension which provides enhanced cookie privacy (also backported to Firefox 2.0.0.5). Improvements to layout and scaling precision across numerous screen and printer resolutions. Adding of FUEL JavaScript library for extension developers. Rewrite of Page Info dialog. Upgrade to Cairo 1.4.2. More Cocoa regression fixes. Places (bookmark and history service based on SQLite) used by default, but no front-end changes. Breakpad used as crash reporter on Windows and Mac OS X, superseding closed-source Talkback. Password manager rewrite. Support for Growl and native widgets within forms for Mac OS X. Upgrade of SQLite to version 3.3.17, leading to increased cookie performance due to transition of cookie service to SQLite. Site-specific preference service, used initially for text zoom, allowing zoom setting to remain on each website. Support for native widgets within forms for Linux. New Quit dialog handles multiple windows more elegantly and allows users to save session. Autoscroll rewrite: numerous bug fixes and significant performance gain. Fixes to the use of units within the download manager. Various Places bug fixes. More APIs implemented from WHATWG specs, such as ability to read files from file selection fields without need to upload and cut/copy/paste events, and cross-site XMLHttpRequest. New protocol-handling dialog. Experimental full-page zoom support, but no UI to control it. Numerous Mac OS X bug fixes, but Mac OS X 10.3 no longer supported for Gecko 1.9. General bug fixes. New, basic UI for tagging bookmarks. Remember password prompt changed to non-modal information bar. Malware blacklist support. New UI for FTP and File protocol listings. Applications pane added to preferences. Basic support for web-based protocol handlers. Changes during betas New UI improvements, including redesigned location bar, Places Organizer, Smart Bookmarks. Various stability and performance improvements. New UI improvements, including redesigned buttons and location bar. Different default native themes for each operating system. Upgraded to SQLite 3.5.4. Various stability and performance improvements. New UI improvement, including improved default themes for different operating systems. Various improvements in speed and resource usage. Further improved themes to match various operating systems, JavaScript engine optimizations for speed, improved Places organizer. |
| 3.0.1 | | July 16, 2008 | Security and stability update. |
| 3.0.2 | | September 23, 2008 | Regular security and stability update. |
| 3.0.3 | | September 26, 2008 | Bug fix for retrieving and saving passwords. |
| 3.0.4 | | November 12, 2008 | Regular security and stability update. |
| 3.0.5 | | December 16, 2008 | Regular security and stability update. |
| 3.0.6 | | February 3, 2009 | Regular security and stability update. |
| 3.0.7 | | March 4, 2009 | Regular security and stability update. |
| 3.0.8 | | March 27, 2009 | Off-cycle security update. |
| 3.0.9 | | April 21, 2009 | Regular security and stability update. |
| 3.0.10 | | April 27, 2009 | Off-cycle stability update. |
| 3.0.11 | | June 11, 2009 | Regular security and stability update. |
| 3.0.12 | | July 21, 2009 | Regular security and stability update. |
| 3.0.13 | | August 3, 2009 | Regular security and stability update. |
| 3.0.14 | | September 9, 2009 | Regular security and stability update. |
| 3.0.15 | | October 27, 2009 | Regular security and stability update. |
| 3.0.16 | | December 15, 2009 | Regular security and stability update. |
| 3.0.17 | | January 5, 2010 | Off-cycle stability update. |
| 3.0.18 | | February 17, 2010 | Regular security and stability update. |
| 3.0.19 | | March 30, 2010 | Regular security and stability update. End-of-life 3.0.x product line |

### Firefox 3.5

Version 3.5, codenamed Shiretoko, 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. 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, 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. 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. 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. 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 touchpad support was also added to the release, including gesture support like pinching for zooming and swiping for back and forward. Firefox 3.5 also features an updated logo.
Release history of Firefox 3.5 :
| Version | Codename | Release date | Release type and highlights |
| 3.5 | Shiretoko | June 30, 2009 | Official version 3.5 release. Gecko version 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. Changes during alphas Web standards improvements. Text API for the <canvas> element. Support for using border images. Support for DOM query selectors. Improvements to Smart Location Bar. New tab-switching behavior. Changes during betas Web standards improvements in Gecko layout engine. Added support for CSS 2.1 and CSS 3 properties. New tab-switching shortcut that shows previews of the tab user is switching to. Improved control over Smart Location Bar using special characters to restrict your search. Support for new web technologies. Available in 54 languages. Added new Private Browsing Mode. Added functions to facilitate clearing recent history by time as well as to remove all traces of a website. New support for web worker threads. New TraceMonkey JavaScript engine on by default for web content. Improvements to Gecko layout engine, including speculative parsing for faster content rendering. Removed new tab-switching behavior based on user feedback. Support for new web technologies. Available in 64 languages. Improved new Private Browsing Mode. Improvements to web worker thread support. Improved performance and stability with the TraceMonkey JavaScript engine. New native JSON support. Improvements to Gecko layout engine, including speculative parsing for faster content rendering. Support for new web technologies such as <video> and <audio> elements, W3C Geolocation API, JavaScript query selectors, CSS 2.1 and 3 properties, SVG transforms and offline applications. Available in 70 languages. Improved tools for controlling private data, including Private Browsing Mode. Better performance and stability with new TraceMonkey JavaScript engine. Ability to provide Location Aware Browsing using web standards for geolocation. Support for native JSON, and web worker threads. Improvements to Gecko layout engine, including speculative parsing for faster content rendering. Support for new web technologies such as HTML5 <video> and <audio> elements, downloadable fonts and other new CSS properties, JavaScript query selectors, HTML5 offline data storage for applications, and SVG transforms. |
| 3.5.1 | | July 16, 2009 | Off-cycle security and stability update. |
| 3.5.2 | | August 3, 2009 | Regular security and stability update. |
| 3.5.3 | | September 9, 2009 | Regular security and stability update. |
| 3.5.4 | | October 27, 2009 | Regular security and stability update. |
| 3.5.5 | | November 5, 2009 | Off-cycle security and stability update. |
| 3.5.6 | | December 15, 2009 | Regular security and stability update. |
| 3.5.7 | | January 5, 2010 | Off-cycle stability update. |
| 3.5.8 | | February 17, 2010 | Regular security and stability update. |
| 3.5.9 | | March 30, 2010 | Regular security and stability update. |
| 3.5.10 | | June 22, 2010 | Regular security and stability update. |
| 3.5.11 | | July 20, 2010 | Regular security and stability update. |
| 3.5.12 | | September 7, 2010 | Regular security and stability update. |
| 3.5.13 | | September 15, 2010 | Off-cycle stability update. |
| 3.5.14 | | October 19, 2010 | Regular security and stability update. |
| 3.5.15 | | October 27, 2010 | Off-cycle security update. |
| 3.5.16 | | December 9, 2010 | Regular security and stability update. |
| 3.5.17 | | March 1, 2011 | Regular security and stability update. |
| 3.5.18 | | March 22, 2011 | Off-cycle security update. Blacklists a few invalid HTTPS certificates. |
| 3.5.19 | | April 28, 2011 | Regular security and stability update. End-of-life 3.5.x product line |

### Firefox 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. 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 plugin is allowed to be unresponsive before the plugin quits.
Release history of Firefox 3.6 :
| Version | Codename | Release date | Release type and highlights |
| 3.6 | Namoroka | January 21, 2010 | Official Firefox 3.6 release. Gecko version 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. Changes during alphas Compositor (Phase 1), which moves Gecko to using one native widget per top-level content document. A new focus model. The chromedir attribute has been replaced with a pseudoclass. Several new CSS3 properties including background size and gradients for background images. Speed improvements to the TraceMonkey JavaScript engine. Startup and responsiveness improvements throughout the application. Changes during betas Users can now change their browser's appearance with a single click, with built in support for Personas. Firefox 3.6 will alert users about out of date plugins to keep them safe. Open, native video can now be displayed full screen, and supports poster frames. Support for the WOFF font format. Improved JavaScript performance, overall browser responsiveness and startup time. Support for new CSS, DOM and HTML5 web technologies. A mechanism to prevent incompatible software from crashing Firefox. A change to how third-party software integrates with Firefox to increase stability. The ability to run scripts asynchronously to speed up page load times. Added support for the HTML5 File API. |
| There was no version 3.6.1. ||||
| 3.6.2 | | March 22, 2010 | Security and stability update. |
| 3.6.3 | | April 1, 2010 | Quick turn-around security update. |
| 3.6.3plugin1 | Lorentz | April 8, 2010 | First Firefox "Lorentz" beta, followed by 7 more Firefox 3.6.4 pre-release builds, all codenamed "Lorentz". |
| 3.6.4 | Lorentz | June 22, 2010 | Regular security and stability update. Provides uninterrupted browsing for Windows and Linux users when there is a crash in the Adobe Flash, Apple QuickTime or Microsoft Silverlight plugins. |
| There was no version 3.6.5. ||||
| 3.6.6 | | June 26, 2010 | Off-cycle stability update. Modified crash protection feature to increase amount of time plugins allowed to be non-responsive before being terminated. |
| 3.6.7 | | July 20, 2010 | Regular security and stability update. |
| 3.6.8 | | July 23, 2010 | Off-cycle stability update. |
| 3.6.9 | | September 7, 2010 | Regular security and stability update. Also added support for X-FRAME-OPTIONS HTTP response header to help prevent clickjacking and removed option to enable experimental HTML5 parser via user preference html5.enable in about:config. |
| 3.6.10 | | September 15, 2010 | Off-cycle stability update. |
| 3.6.11 | | October 19, 2010 | Regular security and stability update. |
| 3.6.12 | | October 27, 2010 | Off-cycle security update. |
| 3.6.13 | | December 9, 2010 | Regular security and stability update. |
| 3.6.14 | | March 1, 2011 | Regular security and stability update. |
| 3.6.15 | | March 4, 2011 | Off-cycle stability update. Fixed issue where some Java applets failed to load in Firefox 3.6.14. |
| 3.6.16 | | March 22, 2011 | Off-cycle security update. Blacklisted several invalid HTTPS certificates. |
| 3.6.17 | | April 28, 2011 | Regular security and stability update. |
| 3.6.18 | | June 21, 2011 | Regular security and stability update. |
| 3.6.19 | | July 11, 2011 | Off-cycle stability update. Turned off downloadable font support for users running Mac OS X 10.7 due to an underlying platform bug. No changes made on Windows side. |
| 3.6.20 | | August 16, 2011 | Regular security and stability update. |
| 3.6.21 | | August 30, 2011 | Off-cycle security update. Blacklisted a compromised HTTPS certificate. |
| 3.6.22 | | September 6, 2011 | Off-cycle security update. |
| 3.6.23 | | September 27, 2011 | Regular security and stability update. |
| 3.6.24 | | November 8, 2011 | Regular security and stability update. |
| 3.6.25 | | December 20, 2011 | Regular security and stability update. |
| 3.6.26 | | January 31, 2012 | Regular security and stability update. |
| 3.6.27 | | February 17, 2012 | Off-cycle security update. |
| 3.6.28 | | March 13, 2012 | Regular security and stability update. End-of-life 3.6.x product line on April 24, 2012. Last release for Mac OS X Tiger and PowerPC Macs. |

### Firefox 4

On October 13, 2006, Brendan Eich, Mozilla's then-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. 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.
After five "Alpha" releases, twelve "Beta" releases, and two "Release Candidate" versions, Firefox 4 was released on March 22, 2011, originally Firefox 3.7 (Gecko 1.9.3) during its alpha stage, brought a new user interface and is said to be faster. Early mockups of the new interface on Windows, Mac OS X, and Linux were first made available in July 2009. Other new features included improved notifications, tab groups, "switch to tab" where opened tabs can be searched through the address bar, application tabs, a redesigned add-on manager, integration with Firefox Sync, and support for multi-touch displays.
Firefox 4 was based on the Gecko 2.0 engine, which added or improved support for HTML5, CSS3, WebM, and WebGL. It also included a new JavaScript engine (JägerMonkey) and better XPCOM APIs.
Release history of Firefox 4 :
| Version | Codename | Release date | Release type and highlights |
| 4.0 | Tumucumaque | March 22, 2011 | Official Firefox 4.0 release. Gecko version 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. Changes during alphas Support for WebGL(Disabled by default, but can be enabled by changing a preference). Support for new CSS, DOM and HTML5 web technologies. On Windows and Linux, plugins (such as Flash and Silverlight) are now isolated from Firefox. Plugin crashes will not kill Firefox itself, and unresponsive plugins are automatically restarted. The SSL security system has been changed to fix a renegotiation flaw. Link history lookup is now performed asynchronously on a thread. Loading the HTML5 specification no longer causes very long browser pauses. Some JavaScript engine improvements. The stop and reload buttons have been merged when they are adjacent on the toolbar. More performance and stability improvements. An experimental Direct2D rendering backend on Windows is available, turned off by default. Significant API improvements are available for JS-ctypes. Mozilla now uses an infallible allocator. Additional fixes for multi-process plugins. CSS :visited selectors have been changed to block ways that websites can quickly check a user's browsing history. Currently loaded web pages are shown in the location bar autocomplete list, allowing switching to existing tabs. The beta version of Adobe Flash is now run in a separate process on Mac OS X Snow Leopard (10.6). Full-screen video on Windows is now rendered using hardware acceleration when available. Mozilla has implemented the Core Animation rendering model for plugins on Mac OS X. Linux builds are now built with -fomit-frame-pointer. Support for new SVG and HTML5 web technologies. Added WebM video playback. First official release to include linux-x86_64 and mac-x86_64 builds and first regular release to include WebM video playback. New Addons Manager (placeholder UI only). Tab on Top can now be implemented. Firefox now uses hardware acceleration for video playback. Cocoa NPAPI support. ChromeWorker with jsctypes support. Lazy frame construction for faster dynamic pages. JavaScript performance improvements. Loading the URL about:memory now shows how much memory is used by different parts of Firefox. More Performance improvement and support for new CSS and HTML5 web technology. Changes during betas Tabs are now on top by default on Windows. On Windows Vista and Windows 7 the menu bar has been replaced with the Firefox button. The Bookmarks Toolbar has been replaced with a Bookmarks Button by default (you can switch it back if you'd like). Support for more HTML5 technologies. Tabs are now on top by default on OSX. App Tabs can now be created. Content animation using CSS Transitions can now be implemented. Responsiveness and scrolling improvements from the new retained layers layout system. JavaScript speed improvements due to engine optimizations. Changes to how XPCOM components are registered in order to help startup time and process separation. 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 (used for things like graphics and animations) more efficiently. Firefox Sync is now included. Panorama, a new feature that gives users a visual overview of all open tabs, allowing them to be sorted and grouped, is now included. An experimental API is included to provide more efficient Javascript animations. Firefox now supports the HTML5 video "buffered" property. Support for the new proposed Audio Data API. Direct2D Hardware Acceleration is now on by default for Windows 7 users. Firefox button has a new look for Windows Vista and Windows 7 users. Support for HSTS security protocol allowing sites to insist that they only be loaded over SSL. Fixed a stability issue affecting Windows users. Fixed an issue causing rendering errors with plugins affecting Mac OS X users. Uses JägerMonkey, a new, faster JavaScript engine. WebGL is enabled by default on Windows and Mac OS X. Certain rendering operations are now hardware-accelerated using Direct3D 9 on Windows XP, Direct3D 10 on Windows Vista and 7, and OpenGL on Mac OS X. Improved web typography using OpenType with support for ligatures, kerning and font variants. HTML5 Forms API makes web based forms easier to implement and validate. The Firefox Sync setup experience has been greatly improved across desktop and mobile devices. Speed, functionality, and compatibility improvements to WebGL. Additional polish for the Firefox Add-ons Manager. 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. Compatibility and stability improvements when using Adobe Flash on Mac OS X. Improvements in memory usage. Support for a graphics driver blacklist to improve stability. Support for the proposed Do Not Track ("DNT") header. Connection status messages are now shown in a small overlay. WebGL has been re-enabled on Linux. The default homepage design has been refreshed. Firefox no longer switches into offline mode automatically. Increased performance while viewing Flash content. Improved plugin compatibility with hardware acceleration enabled. Hovering over links now displays the URL at the bottom of the window rather than in the location bar. General stability, performance, and compatibility improvements. Config option to limit the number of tabs loaded at once during the session restore, which also made possible to lazy load tabs (the latter behavior was put in preferences in version 8). Changes during release candidates General stability, performance, and compatibility improvements. Blacklisted a few invalid HTTPS certificates. Updated localizations for 29 locales. Added Vietnamese localization, bringing the total languages available in Firefox 4 to 83. |
| 4.0.1 | Macaw | April 28, 2011 | Regular security and stability update. Fixed several security issues Fixed several stability issues End-of-life 4.0.x product line on June 21, 2011. |