Mozilla Firefox 21 Released With New Features

Firefox 21 is no longer in Beta and is now available for download with improved performance and various new features. However, the official release is still a few hours away, but Mozilla has already uploaded it to its servers, for users to download.


Mozilla has added various new features in Firefox 21 and also made some major changes to existing one. It also features several bug fixes, although there are still a few issues left unresolved.

No official Firefox 21 changelog is released yet, but the release notes reveals all.

New features added in Firefox 21

  • Enhanced three-state UI for Do Not Track
  • Suggestions on how to improve the application startup time when needed
  • Preliminary implementation of Firefox Health Report
  • Added support for <main> element
  • Implemented scoped stylesheets

Changed Features of Firefox 21

  • Ability to Restore removed thumbnails on New tab Page
  • Add-ons History API removals in Places
  • CSS -moz-user-select:none selection changed to improve compatibility with -webkit-user-select:none (bugs 816298)
  • Graphics related performance improvements (bugs 809821)
  • Removed E4X support from SpiderMonkey

Bugs Fixed in Firefox 21

  • Some function keys may not work when pressed
  • Browsing and Download history clearing needs unification to avoid confusion on clearing download history

Unresolved Issues in Firefox 21

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

‘Three state Do Not Track’ is one of the main features added to the new Firefox 21. It lets you decide if you want to be tracked with the cookies of any websites or not. You can evade the tracking cookies of any website you don’t visit including the advertising programs and analytic services.

“The Firefox Health Report” included in Firefox 21 keeps you posted with information about your browser’s stability and performance over time. It also lets you know how various configurations could affect the performance of Firefox.

Download Link:  Firefox 21 (EN-US).

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Shiwangi Peswani is a qualified writer and a blogger, who loves to dabble with and write about computers and the Internet. While focusing on and writing on technology topics, her varied skills and experience enables her to write on any topics which may interest her.


  1. Robert Nielsen

    I installed Firefox 21, but the jump list from the taskbar doesn’t work…I’ve reset jumplists, cleared out temp files, uninstalled and reinstalled, and still not seeing my frequently visited websites when I right click on the taskbar icon.

  2. Robert Nielsen

    A question…what does this mean??

    “Browsing and Download history clearing needs unification to avoid confusion on clearing download history”

  3. shiwangi peswani

    Its working fine here. Did you try the following? Backup your browser settings, uninstall Firefox, use CCleaner, restart and then install Firefox? If not maybe you could create a new profile on Firefox, transfer all your settings, etc to the new profile, and see if it helps

  4. Robert Nielsen

    Tried that, still no jump list when I reinstalled Firefox. I don’t know how to back up/transfer settings, though.

  5. Robert Nielsen

    Okay…just tried again…ran CCleaner, restarted, reinstalled Firefox…and so far, after visiting several web pages, I have only *one* link in the jump list…the bookmark file I imported. None of the websites I visited are showing up.

  6. gcacars

    is the worst firefox that I’ve ever installed, lots of bugs

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