Here is what is new and changed in Firefox 87.0

Mozilla plans to release Firefox 87.0 Stable and Firefox 78.9 ESR to the public on March 23, 2021. The browser will be released later on the day, and should be available if you are reading this after March 23, 2021.

The new versions of Firefox are available as automatic updates but also as direct downloads from Mozilla's main website and third-party sites as well.

All development versions of Firefox are released around the same time. Firefox Beta and Firefox Developer are updated to Firefox 88, Firefox Nightly is updated to version 89, and Firefox for Android will also be updated to version 87.0 eventually (the release was delayed somewhat recently).

Check out our Firefox 86.0 release overview in case you missed it.

Executive Summary

Firefox 87 introduces SmartBlock, a feature to reduce website breakage when using private browsing or strict enhanced tracking protection.
The default HTTP Referrer policy will trim the path so that only the domain name is submitted for cross-origin requests.
Firefox 87 includes security fixes.

Firefox 87.0 download and update

Firefox 87.0 and Firefox ESR 78.9 are available via the browser's automatic update feature after the official release later on March 23, 2021. You can verify the installed version by selecting Menu > Help > About Firefox; this will also run a check for updates.

Manual downloads are also available. The following pages list direct downloads for supported Firefox channels.

New features and improvements

firefox 87 release notes

Less website breakage

Firefox users who use the browser's private browsing mode or have set Enhanced Tracking Protection to Strict, benefit from a new feature that Mozilla calls SmartBlock.

SmartBlock is designed to reduce breakage on websites by using stand-in scripts on sites so that these load properly.

HTTP Referrer is trimmed

Starting in Firefox 87, the browser will trim the HTTP Referrer for all cross-origin requests, e.g. when a site loads a third-party resource such as an image or a stylesheet.

Instead of revealing the full path of the webpage the user is on, only the domain name will be revealed.

Check out our coverage of the feature here: Firefox 87 to limit the referrer for all cross-origin requests

Other changes

Highlight All of the Find in Page feature displays marks on the scrollbar that correspond to matches on the page.
Built-in support for he Mac OS built-in screen reader, VoiceOver.
Support for the Silesian locale.
Several accessibility related fixes.
The Backspace key is now disabled as a navigation shortcut in order to prevent data loss when filling out forms. The shortcut Alt-Left-Arrow or Command-Left-Arrow may be used instead. Firefox users who want to restore the functionality may set browser.backspace_action to 0 on about:config.
The menu items Synced tabs, Recent highlights and Pocket list were removed from the Library menu.
The Help menu has been simplified.

Firefox for Android

Coming once it is released.

Developer Changes

Starting March 15, 2021, all extension developers must enable two-factor authentication to better protect their accounts.
The Page Inspector tool supports the simulation of prefers-color-scheme media queries and options to toggle the :target pseudo class for the currently selected element.
Other Page Inspector improvements include that table-layout and scroll-padding properties are marked as inactive for non-table elements or non-scrollable elements.
The <link> element is no longer matched by :link, :visited, or :any-link.
Several Firefox-specific theme-related media features, including moz-windows-classic, moz-scrollbar-end-forward, or -moz-menubar-drag, have been disabled for use in webpages.
Users of enterprise authentication services that require that TLS client certificates are sent in CORS preflight requests may enable network.cors_preflight.allow_client_cert to allow that.
The policies.json file is no longer ignored if policies are specified on Windows (GPO) or Mac OS (configuration profiles).

Known Issues