See what landed recently in Firefox Nightly!

Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.

137.0a1 Firefox Nightly

February 3, 2025

Version 137.0a1, first offered to Nightly channel users on February 3, 2025

Firefox Nightly gets updated every day and as a consequence, the release notes for the Nightly channel are updated continuously to reflect features that have reached sufficient maturity to benefit from community feedback and bug reports.

Warning: Features listed here may or may not make a final release of Firefox.

In addition to these release notes, you can follow ongoing development on our @FirefoxNightly X account, our @FirefoxNightly Mastodon account as well as read our Nightly Blog.

You can interact with other Firefox Nightly users and give your feedback to Mozilla staff in the Nightly Matrix room on chat.mozilla.org.

New

  • Starting with Firefox Nightly 135, the DevTools toolbox colors have been updated to have higher contrast than the regular theme when in High Contrast Mode. Note that this change will only be activated when all of these conditions are met:

    • High Contrast Mode is enabled for the system.
    • In about:settings, in the "Colors" popup, "Use system colors" is checked, and "Override the colors specified by the page with your selections above" is set to something else than "Never".
    • In DevTools settings, the selected Theme is "Auto".
    Bug 1932642

  • Starting with Firefox Nightly 134, Firefox can now selectively unblock certain social media embeds in ETP Strict or Private Browsing mode, allowing users to access blocked content without decreasing their overall protection level.

    Shield menu with the new smartblock option

    Instagram content marhed as blocked

    Bug 1920776

  • Starting with Firefox 136, profile management is now available in Nightly builds. Users can now more easily create and switch between different profiles.

    Bug 1931006

Changed

  • Starting with Firefox for Android 131, HLS playlist support was deprecated in Nightly builds. Extended testing showed no adverse impact as newer playback technologies have been widely adopted by websites.

    Bug 1911651

  • Starting with Firefox Nightly 135, third-party tracking cookies are now protected by Total Cookie Protection instead of being blocked by default.

    Bug 1935156

Developer

Web Platform

  • Starting with Firefox 135, the Temporal proposal, a better version of Date, is now available for experimentation in Nightly builds behind the javascript.options.experimental.temporal preference. For more details, see https://tc39.es/proposal-temporal/docs/.

    Bug 1912757

  • Starting with Firefox 136, support for the SVG 2 path API is now available in Nightly builds

    Bug 1934525

  • Starting with Firefox 136, support for the SVG discard element is now available in Nightly builds.

    Bug 1069931

  • Starting with Firefox 136, scroll-driven animations is enabled in Nightly builds.

    Bug 1817303

  • Starting with Firefox 136, support for the hyphenate-limit-chars property is now available in Nightly builds. This property enables authors to have greater control over the use of automatic hyphenation.

    Bug 1521723

Get the most recent version

All Firefox Nightly downloads