Firefox 93.0 release: here is what is new and changed

Firefox 93.0 will be released later today, if you are reading this on October 5, 2021. The new stable version of Mozilla's Firefox web browser is a feature update that includes security and stability fixes as well.

All other Firefox channels are updated around the same time. Firefox Developer and Beta versions are upgraded to version 94, Firefox Nightly to version 95, and Firefox for Android will also be updated to version 93.

The last Firefox 78.x ESR version is released today. Mozilla released Firefox 91.0 ESR in August, and it will become the only supported ESR channel when Firefox 94.0 is released next month.

You can check out Firefox 92.0 release information, in case you missed it or want to read it again.

Executive Summary

Firefox 78.15 ESR is the last release of the branch, and the only supported version of Firefox to support Adobe Flash and Mac OS X versions 10.11 and older.
Firefox supports the AVIF image format by default
WebRender should be enabled on all systems now.
Firefox 92.0 includes security updates.

Firefox 93.0 download and update

Firefox installations will be updated automatically on most systems, as Firefox checks for updates automatically in intervals to download new updates automatically.

To check the installed version, go to Menu > Help > About Firefox. Note that this will also run a manual check for updates and will install new versions that are found during the scan.

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

New features and improvements

AVIF format support is enabled by default

Mozilla planned to enable AVIF support in Firefox 92, but postponed the release. AVIF support is enabled by default in Firefox 93. It is an open format that offers "excellent compression" and has no patent restrictions.

The Firefox implementation supports still images, "with colorspace support for both full and limited range colors, and image transforms for mirroring and rotation", but no animated images.

Tip: open this test site in your browser to see if it supports AVIF.

Unload tabs on Windows when memory is critically low

Firefox includes a new tab unloading feature on Windows. It is an automated feature that will unload tabs if available "system memory is critically low".

Tabs are unloaded based on last access time, memory usage and other attributes.

Mozilla hopes that the feature will reduce the number of memory-related crashes that users of Firefox experience.

See our full coverage of Firefox's new tab unloading feature here..

Insecure downloads are blocked by default