Firefox Nightly
Release Notes

Starting with Firefox 129, Firefox Nightly will automatically try to use a secure HTTPS connection whenever possible when loading a page. This behavior is known as "HTTPS-First", or "HTTPS Upgrades", and has been the default in Firefox's private browsing mode since Firefox 91. Here is a blog post from when this feature was introduced in Private Browsing.

You can now show tabs from other devices in the Tab overview menu.

Starting with Firefox 133, Firefox follows the model HTML specification for transient user activation more closely in Nightly builds. This change makes popup blocking less strict in cases where previous versions of Firefox were overly aggressive, reducing erroneous blocking prompts.

Firefox now supports touchpad hold gestures on Linux. This means that kinetic (momentum) scrolling can now be interrupted by placing two fingers on the touchpad.

GPU-accelerated Canvas2D is enabled by default on Windows.

Desktop mode browsing is now enabled by default for large devices on Firefox for Android. This can be controlled via a preference under Settings in "Site settings" previously named "Site permissions".

Firefox now has a new anti-tracking feature enabled in Enhanced Tracking Protection "strict" mode: Bounce Tracking Protection. This protection detects bounce trackers based on redirect behavior and periodically purges their cookies and site data to prevent tracking.

If we have the server time, we adjust the "expire" attribute value by adding the delta between the server and the local times. If the current time is set in the future, we consider valid cookies that are not expired for the server.

Fix for MFSA 2024-51 included in 2024-10-08 builds and newer.

Fixed an issue that started with macOS Sonoma where the emoji picker would open and immediately close when opened with the Cmd+Ctrl+Space shortcut.

Thanks to research by Carlos Duarte do Nascimento (Chester) and :bintoro, and a patch by Carlos Duarte do Nascimento (Chester), we have been able to fix this universally for this shortcut and similar shortcuts going forward.

Fixed an issue that started with macOS Sonoma where the emoji picker would also insert the character "e" in the selected text field/box when opening the emoji picker using the Fn+e shortcut.

We have also fixed this for similar shortcuts using the Fn key.

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.

Starting with Firefox 133, the Developer Tools debugger editor now uses Codemirror 6 in Firefox Nightly builds. Developer Tools debugger users should see performance improvements with larger files.

Starting with Firefox Nightly 131, support for the non-mandatory options argument to getBBox will get the bounding box of the element, including its stroke (e.g. element.getBBox({"stroke": true})). (Learn more)

Firefox now supports the keepalive option in the Fetch API. This feature allows developers to make HTTP requests that can continue to run even after the page is unloaded, such as during page navigation or closing.

Firefox now supports Permissions API in Worker Context.

Starting with Firefox 133, basic features of contenteditable="plaintext-only" are now supported in Firefox Nightly. Firefox still uses <br> elements for line breaks in contenteditable="plaintext-only" even when white-space is pre, pre-line, or pre-wrap. Therefore, textContent of editing host returns one line text even if there are multiple lines.

Firefox now dispatches beforetoggle events just before a dialog opens and toggle events after the dialog closes, matching the behavior of popovers.

Methods are now available on UInt8Array to convert to and from Base64 and hexadecimal encodings. This is an implementation of a Stage 3 TC39 proposal, for more details see the proposal text.

Added support for image decoding as part of the WebCodecs API. This allows for decoding of images from the main and worker threads.