Download Firefox 51

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We don't have any change log information yet for version 87.0 of Mozilla Firefox for PC Windows. Sometimes publishers take a little while to make this information available, so please check back in a few days to see if it has been updated. Users on 64-bit Windows who download Firefox can get our 64-bit version by default. That means you get a more secure version of Firefox, one that also crashes a whole lot less. In our tests so far, 64-bit Firefox reduced crashes by 39% on machines with 4GB of RAM or more.

Warning: Firefox now includes downgrade protection to prevent corruption of user profile data. If you install an older version, you'll be prompted to create a new Firefox profile.

If there is a problem with a new version of Firefox, some people may want to downgrade Firefox to a previous version but we do not recommend this. The latest Firefox version includes security updates so downgrading to an older version leaves you more vulnerable to attacks and usually doesn't fix the problem. This article gives you some alternatives to downgrading and links to older versions of Firefox if you do choose to downgrade.

Table of Contents

Problems with an update are usually not caused by the new version of Firefox, but rather the update process. In most cases, installing a previous version will not help. Instead, see:

Note: Other problems can be solved with the Refresh Firefox feature. It restores Firefox to its default state while saving your essential information.

Ensure all security and security-related software is fully updated. Some security software will need to be upgraded to a new version so that it is compatible with each Firefox version update.

Optional software bundled with security software also may need updating. Such software may not be essential for your security but, if outdated, may interfere with the use of Firefox or cause Firefox to crash.

If you still want to downgrade, you can visit Mozilla's directory of older Firefox versions using the links below. Please note, however, that using older versions can make Firefox insecure and more vulnerable to attacks and scams. We recommend that you always use the newest version of Firefox.
Warning: Old Firefox versions pose a significant security risk.
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Important: By default, Firefox is set for automatic updates. To prevent Firefox from automatically updating itself after you install an older version, you'll need to change your Firefox update settings: In the Menu bar at the top of the screen, click Firefox and select Preferences.Click the menu button and select ... In the General panel, go to the Firefox Updates section.

Instead of downgrading to an older, insecure version of Firefox and changing your update settings, you should consider these alternatives:

Install Firefox Extended Support Release.Firefox Extended Support Release (ESR) is an official version of Firefox developed for large organizations such as universities and businesses. Firefox ESR does not come with the latest features, but it does have the latest security and stability fixes. For more information, see the article Switch to Firefox Extended Support Release (ESR) for personal use.

Download Firefox 51 For Windows

Use the latest version of another browser. If you are not satisfied with the current Firefox version or it simply is not working right now, there are alternative browsers that you can use to browse the web.

A faster, more secure and customizable Web browser.

Mozilla Firefox is a fast, light and tidy open source web browser. At its public launch in 2004 Mozilla Firefox was the first browser to challenge Microsoft Internet Explorer’s dominance. Since then, Mozilla Firefox has consistently featured in the top 3 most popular browsers globally and this is set to continue thanks to the release of Firefox 30. The key features that have made Mozilla Firefox so popular are the simple and effective UI, browser speed and strong security capabilities. The browser is particularly popular with developers thanks to its open source development and active community of advanced users.

Easier Browsing

Mozilla put of a lot of resources into creating a simple but effective UI aimed at making browsing quicker and easier. They created the tab structure that has been adopted by most other browsers. In recent years Mozilla has also focused on maximizing browsing area by simplifying toolbar controls to just a Firefox button (which contains settings and options) and back/forward buttons. The URL box features direct Google searching as well as an auto predict/history feature called Awesome Bar. On the right side of the URL box there are bookmarking, history and refresh buttons. To the right of the URL box is a search box which allows you to customize your search engine options. Outside of that a view button controls what you see below the URL. Next to that you have the download history and home buttons.

Speed

Mozilla Firefox boasts impressive page load speeds thanks to the excellent JagerMonkey JavaScript engine. Start up speed and graphics rendering are also among the quickest in the market. Firefox manages complex video and web content using layer-based Direct2D and Driect3D graphics systems. Crash protection ensures only the plugin causing the issue stops working, not the rest of the content being browsed. Reloading the page restarts any affected plugins. The tab system and Awesome Bar have been streamlined to launch/get results very quickly too.

Security

Firefox was the first browser to introduce a private browsing feature which allows you to use the internet more anonymously and securely. History, searches, passwords, downloads, cookies and cached content are all removed on shutdown. Minimizing the chances of another user stealing your identity or finding confidential information. Content security, anti-phishing technology and antivirus/antimalware integration ensures your browsing experience is as safe as possible.

Personalisation & Development

One of the best features of the Firefox UI is customization. Simply right click on the navigation toolbar to customize individual components or just drag and drop items you want to move around. The inbuilt Firefox Add-ons Manager allows you to discover and install add-ons within the browser as well as view ratings, recommendations and descriptions. Read about the top recommended add-ons for Mozilla Firefox on TechBeat. Thousands of customizable themes allow you to customize the look and feel of your browser. Site authors and developers can create advanced content and applications using Mozilla’s open source platform and enhanced API.

  • Firefox keeps getting faster as a result of significant updates to SpiderMonkey, our JavaScript engine, you will now experience improved page load performance by up to 15%, page responsiveness by up to 12%, and reduced memory usage by up to 8%. We have replaced part of the JavaScript engine that helps to compile and display websites for you, improving security and maintainability of the engine at the same time.
  • Firefox introduces HTTPS-Only Mode. When enabled, this new mode ensures that every connection Firefox makes to the web is secure and alerts you when a secure connection is not available. You can enable it in Firefox Preferences.
  • Pinch zooming will now be supported for our users with Windows touchscreen devices and touchpads on Mac devices. Firefox users may now use pinch to zoom on touch-capable devices to zoom in and out of webpages.
  • Picture-in-Picture now supports keyboard shortcuts for fast forwarding and rewinding videos: use the arrow keys to move forward and back 15 seconds, along with volume controls.
  • When you are presenting your screen on a video conference in Firefox, you will see our improved user interface that makes it clearer which devices or displays are being shared.
  • Selecting a search engine at the bottom of the search panel now enters search mode for that engine, allowing you to see suggestions (if available) for your search terms. The old behavior (immediately performing a search) is available with a shift-click.
  • When Firefox autocompletes the URL of one of your search engines, you can now search with that engine directly in the address bar by selecting the shortcut in the address bar results.
  • We’ve added buttons at the bottom of the search panel to allow you to search your bookmarks, open tabs, and history.
  • Firefox supports AcroForm, which will allow you to fill in, print, and save supported PDF forms and the PDF viewer also has a new fresh look.
  • For the recently released Apple devices built with Apple Silicon CPUs, you can use Firefox 83 and future releases without any change. This release (83) will support emulation under Apple’s Rosetta 2 that ships with macOS Big Sur. We are working toward Firefox being natively-compiled for these CPUs in a future release.
  • Screen reader features which report paragraphs now correctly report paragraphs instead of lines in Google Docs.
  • When reading by word using a screen reader, words are now correctly reported when there is punctuation nearby.
  • The arrow keys now work correctly after tabbing in the picture-in-picture window.
  • For users on macOS restoring a session with minimized windows, Firefox now uses much less power and you should see much longer battery life.
  • Developers can use the scroll badge in the Page Inspector to Debug scrollable overflow. Selecting the badge highlights elements that are causing overflow and marks them with the overflow badge.
83.0
11.19.20
Free
English
53.16 MB
Windows 10, Windows 8, Windows 8.1, Windows 7
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