Version 150.0a1, first offered to Nightly channel users on February 23, 2026
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 Bluesky 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.
Starting with Firefox 148, Nightly builds have stability improvements to the legacy search bar, as well as aligning its search button with the latest designs.
Starting with Firefox 148, the updated Firefox sidebar is now enabled by default for new profiles in Nightly builds. It provides quick access to tools like bookmarks, history, and AI chatbots. Use the settings gear icon at the bottom of the sidebar to add and remove tools, try vertical tabs, or move the sidebar.
Starting with Firefox 148, HDR video on Windows is now supported in Nightly builds. This is considered experimental as we gather feedback before enabling it in regular releases. This feature works best when HDR mode is enabled in Display Settings (this may require a page refresh); otherwise, the display driver is likely to apply a tonemapping effect for non-HDR viewing. Some streaming sites may still not offer HDR video in Firefox. (Learn more)
Starting with Firefox 149, Nightly builds now ship with a new .rpm package for Linux users on Red Hat, Fedora, openSUSE, and other RPM-based distributions.
Starting with Firefox for Android 150, Nightly users can now choose a custom default location for their downloads.
Added support for the GTK emoji picker on Linux, allowing users to insert emoji using the system shortcut (typically Ctrl+.).
You can now reorganize PDF pages directly in the Firefox PDF viewer, including moving, copying, and deleting pages.
Starting with Firefox 148, Nightly builds now support the Document Picture-in-Picture API, which allows web pages to place content in an always-on-top popup.
Starting with Firefox 148, Nightly builds now open an in-page popup for <input type=color> instead of an OS-dependent color picker. Which means it now shows the same behavior on all desktop platforms.
Starting with Firefox 149, you can now set specific color spaces and transparency (alpha) on <input type="color"> elements, with alpha support currently exclusive to Firefox Nightly. While the visual picker hasn't changed yet (tracked in Bug 2007532), it will now output values in your requested format.
Starting with Firefox 149, Nightly builds now support throttling for Web Workers running in inactive tabs. When a tab becomes inactive, Firefox reduces how aggressively its workers can run timeouts.
Local network access restrictions are now being extended to all users. Firefox will require websites to request your permission before connecting to devices on your local network or to apps and services on your device. Previously limited to users with Enhanced Tracking Protection set to Strict, this protection is now rolling out gradually to all users. You can find more details about this on our support page.
This feature is part of a progressive roll out.
Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.
Firefox now supports the ariaNotify API for accessibility notifications (e.g. for screen readers) as a more ergonomic and reliable alternative to ARIA live regions.
Starting with Firefox 150, multiple import maps per document are now supported in Nightly builds, giving web developers more flexibility when structuring and loading modern JavaScript modules. This is considered experimental as we gather feedback before enabling it in regular releases.
This feature is part of a progressive roll out.
Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.
Firefox now supports media element pseudo-classes (e.g., :playing, :paused) to allow more precise styling based on media playback state.
Added support for the highlightsFromPoint() API, which allows web pages to interact with CSS Highlights by returning all Highlights at a given point.
Starting with Firefox 150, the rendering of absolutely positioned elements across multi-column containers and in printing is improved in Nightly builds, ensuring a more accurate element positioning and fragmentation.
Firefox now supports light-dark() on images, just like on colors, which is very useful for supporting dark mode on websites.
The color-mix() function previously accepted only two color values. This limitation has now been removed, allowing the function to accept an arbitrary number of colors.
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