Firefox Nightly

As a reminder, you can follow the general Mozilla news, team work and individual contributors work on Planet Mozilla (which has a RSS feed you can subscribe to). We have 1 to 2 blog posts per day on Planet. planet.mozilla.org

Here's a quick rundown of what we delivered as part of Interop 2025, and what's planned for Interop 2026!

Screenshot of the AI Controls panel in Firefox Nightly preferences

AI Controls are available in Firefox Nightly preferences!

Documentation: support.mozilla.org/kb/firefox-a...

If you find a bug, please report it on Bugzilla via this link: mzl.la/AIControlsFi...

Thanks!

Profile, search and wallpaper bug fixes plus more! – These Weeks in Firefox: Issue 195 – Firefox Nightly News Highlights If you were running into any problems last week opening links from other applications, specifically with Firefox being foregrounded but not opening the URL, this should now be ...

[Nightly Blog] Profile, search and wallpaper bug fixes plus more! – These Weeks in Firefox: Issue 195 blog.nightly.mozilla.org/2026/02/02/p...

AI Controls (formally 'kill switch') are landing in today's Firefox Nightly, and will land with Firefox 148 later this month.

Take note – Split View is ready for testing! – These Weeks in Firefox: Issue 194 – Firefox Nightly News Highlights Shout-out to new contributor Lorenz A, who fixed almost 70 bugs over the past few weeks! Most of this work was modernizing some of our DevTools code to ...

[Nightly Blog] Take note – Split View is ready for testing! – These Weeks in Firefox: Issue 194 blog.nightly.mozilla.org/2026/01/26/t...

FOSDEM 2026 - Browser and web platform

Brussels, here we come! 🦊🇧🇪

Mozilla will be at @fosdem.org next weekend. Swing by our stand to meet our staff and volunteers, and join the "Browser and Web Platform" devroom on Saturday!

Track schedule: fosdem.org/2026/schedul...

Firefox & Linux in 2025 HDR YouTube video clip I used for testing Last year brought a wealth of new features and fixes to Firefox on Linux. Besides numerous improvements and bug fixes, I want to highlight some major achie…

Firefox & Linux in 2025
mastransky.wordpress.com/2026/01/23/f...

Introducing Mozilla’s Firefox Nightly .rpm package for RPM based linux distributions! – Firefox Nightly News After introducing Debian packages for Firefox Nightly, we're now excited to extend that to RPM-based distributions. Just like with the Debian packages, switching to Mozilla’s RPM repository allows Fir...

[Nightly Blog] Introducing Mozilla’s Firefox Nightly .rpm package for RPM based linux distributions! blog.nightly.mozilla.org/2026/01/19/i...

Did you file a bug?

Phasing Out the Older Version of Firefox Sidebar in 2026 – Firefox Nightly News Over a year ago, we introduced an updated version of the sidebar that offers easy access to multiple tools – bookmarks, history, tabs from other devices, and a selection of ...

[Nightly Blog] Phasing Out the Older Version of Firefox Sidebar in 2026 blog.nightly.mozilla.org/2026/01/13/p...

Closing out 2025 Strong – These Weeks in Firefox: Issue 193 – Firefox Nightly News Highlights Special shout-out to volunteer contributor Lorenz A for fixing a huge smattering of bugs in our DevTools code! Lorenz fixed the alignment of numeric values in Netmonitor ...

[Nightly Blog] Closing out 2025 Strong – These Weeks in Firefox: Issue 193 blog.nightly.mozilla.org/2025/12/19/c...

Getting Better Every Day – These Weeks in Firefox: Issue 192 – Firefox Nightly News Highlights Collapsed tab group hover preview is going live in Firefox 145! Nicolas Chevobbe added a feature that collapses unreferenced CSS variables declarations in the ...

[Nightly Blog] Getting Better Every Day – These Weeks in Firefox: Issue 192 blog.nightly.mozilla.org/2025/11/24/g...

two men in suits and ties are waving their hands in a room ALT: two men in suits and ties are waving their hands in a room

bugzilla.mozilla.org/show_bug.cgi...

Firefox JSON Viewer opened for the html entites JSON file We can see the various properties of the JSON file, which are all objects containing a "characters" and a "codepoints" properties. The Console is opened at the bottom. In it, we can see a console message explaining that some data is available (`$json.data` - the parsed JSON object, $json.text` - the original JSON text and `$json.headers` - HTTP request and response headers) There's a console evaluation done with the following snippet: ```js Object.entries($json.data) .filter(([k, v]) => v.codepoints.length > 1) .map(([k, v]) => ({characters: v.characters, htmlEntity: k, codepoints: v.codepoints})) ``` and the result shows an array of objects containing "characters", "htmlEntity" and "codepoints" properties.

The @firefoxdevtools.bsky.social JSON viewer got better in @firefoxnightly.bsky.social : the console offers access to the original json data via `$json`.
This allows to easily manipulate the underlying data to get what you want

Css @ scope was added in Nightly yesterday bugzilla.mozilla.org/1991105 should ship in 146 next month

Extensions UI Improvements and More – These Weeks in Firefox: Issue 191 – Firefox Nightly News Highlights As part of improvements to the extensions panel, an empty state UI has been introduced to help users to understand why their installed extensions may not be listed ...

[Nightly Blog] Extensions UI Improvements and More – These Weeks in Firefox: Issue 191
blog.nightly.mozilla.org/2025/10/27/e...

Smarter Search, Smoother Tools – These Weeks in Firefox: Issue 190 – Firefox Nightly News Highlights Google Lens support has been turned on by default in the latest nightly builds. When Google is your default search engine, and you right click an image ...

[Nightly Blog] Smarter Search, Smoother Tools – These Weeks in Firefox: Issue 190 blog.nightly.mozilla.org/2025/10/06/s...

We are woking on this regression,thttps://bugzilla.mozilla.org/show_bug.cgi?id=1992436
Thanks!

Firefox 144 Highlights: Faster Add-ons, Smarter DevTools, and Tab Group Boosts – These Weeks in Firefox, Issue 189 – Firefox Nightly News Highlights Leo Liu [:leoliu] added a panel for AntiTracking debugging (#1972771) behind devtools.anti-tracking.enabled Alexandre Poirot [:ochameau] added a User-defined badge in the markup view ...

[Nightly Blog] Firefox 144 Highlights: Faster Add-ons, Smarter DevTools, and Tab Group Boosts – These Weeks in Firefox, Issue 189 blog.nightly.mozilla.org/2025/09/22/f...

Add-ons, Fixes, and DevTools Snacks – These Weeks in Firefox: Issue 188 – Firefox Nightly News Highlights The Timer and TODO List widget are now available to be enabled in Firefox Labs on Nightly and Beta: Firefox Desktop about:addons add-on card view ...

[Nightly Blog] Add-ons, Fixes, and DevTools Snacks – These Weeks in Firefox: Issue 188 blog.nightly.mozilla.org/2025/09/19/a...

Webcam previews and more! – These Weeks in Firefox: Issue 187 – Firefox Nightly News Highlights Nicolas Chevobbe added presentational hints in the Inspector's rule-view (#1212289)

[Nightly Blog] Webcam previews and more! – These Weeks in Firefox: Issue 187 blog.nightly.mozilla.org/2025/09/12/w...

Mozilla - Ask a Fox event - Mozilla Community Portal The Mozilla Support platform (a.k.a. SUMO) receives over 20 million visits each month. It’s the go-to place for Firefox users to

Mozilla - Ask a Fox event
community.mozilla.org/campaigns/as...

Firefox Security & Privacy newsletter 2025 Q2 | Attack & Defense
attackanddefense.dev/2025/07/17/f...

Fast, private and secure (pick three): Introducing CRLite in Firefox | The Mozilla Blog We are pleased to announce that Firefox 142 will begin production usage of our brand new certificate revocation system known as CRLite. CRLite makes your b

Fast, private and secure (pick three): Introducing CRLite in Firefox
blog.mozilla.org/en/firefox/c...

Custom Profile Avatars Arrive in Nightly – These Weeks in Firefox: Issue 186 – Firefox Nightly News Highlights Custom avatar picker (and more icon choices) now available in Nightly Tab Groups: 1971230 - [meta] Preview collapsed tab group on hover coming to ...

[Nightly Blog] Custom Profile Avatars Arrive in Nightly – These Weeks in Firefox: Issue 186
blog.nightly.mozilla.org/2025/08/04/c...

Copy Link to Highlight in Nightly – These Weeks in Firefox: Issue 185 – Firefox Nightly News Highlights The Text Fragments creation UI was just activated in Firefox Nightly allowing you to share/reference a link anchor to any text snippet in a page https://mastodon.social/@firefoxnightly/...

[Nightly Blog] Copy Link to Highlight in Nightly – These Weeks in Firefox: Issue 185
blog.nightly.mozilla.org/2025/07/28/c...

As of bugzilla.mozilla.org/1944719 this is now possible

Devotion to Duty

Happy sysadmin day!
xkcd.com/705/

A test page that shows which features of the View Transition API your browser supports, here showing Firefox Nightly (142). It supports not only same-document view transitions but also the view-transition-class property that is specified in the Level 2 specification.

Just spotted: Firefox Nightly already supports view-transition-class from the Level 2 spec.