Firefox 150 release notes for developers (Beta)
This article provides information about the changes in Firefox 150 that affect developers. Firefox 150 is the current Beta version of Firefox and ships on April 21, 2026.
Note: The release notes for this Firefox version are still a work in progress.
Changes for web developers
Changes for add-on developers
- The behavior of
tabs.moveis updated for split views so that:- The order of tabs in a split view can be swapped. (Firefox bug 2016762)
- When the list of tabs includes both split view tabs and places one or more tabs between them, the tabs are moved apart and the split view closed. (Firefox bug 2022549)
Experimental web features
These features are shipping in Firefox 150 but are disabled by default.
To experiment with them, search for the appropriate preference on the about:config page and set it to true.
You can find more such features on the Experimental features page.