Firefox Release

March 23, 2021

Version 87.0, first offered to Release channel users on March 23, 2021

We'd like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox!


  • You’ll encounter less website breakage in Private Browsing and Strict Enhanced Tracking Protection with SmartBlock, which provides stand-in scripts so that websites load properly.

  • To further protect your privacy, our new default HTTP Referrer policy will trim path and query string information from referrer headers to prevent sites from accidentally leaking sensitive user data.

  • The “Highlight All” feature on Find in Page now displays tick marks alongside your scrollbar that correspond to the location of matches found on that page.

  • We’re proud to announce full support for macOS built-in screen reader, VoiceOver.

  • We’ve added a new locale: Silesian (szl)


  • We’ve fixed several significant accessibility issues:

    • Video controls now have visible focus styling and video and audio controls are now keyboard navigable. (Bug 1681007)
    • HTML <meter> is now spoken by screen readers. (Bug 1460378)
    • Firefox now sets a useful initial focus in Add-ons Manager. (Bug 580537)
    • Firefox will now fire a name/description change event when aria-labelledby/describedby content changes. (Bug 493683)
  • Various security fixes.


  • To prevent user data loss when filling out forms, we’ve disabled the Backspace key as a navigation shortcut for the back navigation button. To re-enable the Backspace keyboard shortcut, you can change the about:config preference browser.backspace_action to 0. You can also use the recommended Alt + Left arrow (Command + Left arrow on Mac) shortcut instead.
    Firefox keyboard shortcuts

  • We've removed items from the Library menu that weren't used often or have other access points in the browser: Synced tabs, Recent highlights, and Pocket list.

  • We've simplified the Help menu by reducing redundant items, such as those that point to Firefox support pages that can also be accessed via the Get Help item.

  • In the image context menu, the "View Image Info” menu label has been removed.



  • Developer Information
  • We've greatly simplified the Web Developer menu. Go to Application Menu > Web Developer > Web Developer Tools to access Inspector, Web Console, Debugger, Network Style Error, Performance, Storage Inspector, Accessibility, and Application

  • Developers can now use the Page Inspector to simulate prefers-color-scheme media queries, without having to change the operating system to light or dark mode.

  • Developers can now use the Page Inspector to toggle the :target pseudo-class for the currently selected element in addition to the pseudo-classes that were previously supported: :hover, :active and :focus, :focus-within, :focus-visible, and :visited.

  • There is a number of Page Inspector improvements and bug fixes related to inactive CSS rules:

    • The table-layout property is now marked as inactive for non-table elements.
    • The scroll-padding properties (shorthand and longhand) are now marked as inactive for non-scrollable elements.
    • The text-overflow property was previously incorrectly marked as inactive for some overflow values.
All Firefox downloads