Mozilla Firefox 21.0

Improve your browsing experience with Mozilla's open-source and highly acclaimed Firefox.

Mozilla has switched Firefox to a rapid release development cycle which means new versions will come more frequently. The non-profit organization has promised to push out a new stable build every six weeks.

Awesome Bar

Get to your favorite sites quickly – even if you don’t remember the URLs. Type your term into the location bar (aka the Awesome Bar) and the autocomplete function will include possible matches from your browsing history, bookmarked sites and open tabs.

The Awesome Bar learns as you use it—over time, it adapts to your preferences and offers better-fitting matches. We’ve tweaked it to give you greater control over the results (including privacy settings) and increased performance so you find what you need even faster.

Improved Interface

We’re always looking for ways to make your browsing easier and more efficient. Tabs are above the Awesome Bar to make it easier to focus on the content of the sites you visit. All your menu items are now found in a single button for easy access. Manage your bookmarks in a single button. Find your favorite links without getting bogged down. Your Awesome Bar now features one easy button to stop loading pages or reload pages. The Home button has been moved to the right side of the search-field.

Tabs

Browse multiple sites at once, simply and easily. Each new site appears as a new tab (not a new window) and can be accessed in one click. Take sites you always keep open—like Web mail—off your tab bar and give them a permanent home in your browser. As you’re opening a new tab or typing in the Awesome Bar, Firefox will check to see if you already have that site open. If you do, you’ll be directed to the existing tab so you don’t open a duplicate. Firefox helps you get to your next task faster than ever by displaying a set of thumbnails of your most recently and frequently visited sites every time you open a new tab. You can also customize this page by adding, removing or reorganizing sites to get to where you want to go in one click. If you accidentally close a tab or window, you can reopen it in one click. Just view Recently Closed Tabs or Recently Closed Windows in the History menu and select the tab or window you’d like to reopen. Like to have all 20 of your favorite pages open at once? An elegant new feature lets you scroll through tabs easily to see them all and access the one you want quickly.

What’s New:

• New: Enhanced three-state UI for Do Not Track (DNT)
• New: Firefox will suggest how to improve your application startup time if needed
• New: Preliminary implementation of Firefox Health Report (see FAQ)
• Changed: Ability to Restore removed thumbnails on New tab Page
• Changed: Add-ons History API removals in Places
• Changed: CSS -moz-user-select:none selection Changed to improve compatibility with -webkit-user-select:none (bugs 816298)
• Changed: Graphics related performance improvements (bugs 809821)
• Changed: Removed E4X support from SpiderMonkey
• Developer: Implemented Remote Profiling
• Developer: Integrated, Add-on SDK loader and API libraries into Firefox
• HTML5: Added support for
  element
• HTML5: Implemented scoped stylesheets
• Fixed: Some function keys may not work when pressed (833719)
• Fixed: Browsing and Download history clearing needs unification to avoid confusion on clearing download history (847627)

Known Issues

• Unresolved: If you try to start Firefox using a locked profile, it will crash (see 573369)
• Unresolved: Download statusbar add-on continues downloading files from Normal Browsing, when switching to Private Browsing (see 853463)