Firefox 142 for developers

This article provides information about the changes in Firefox 142 that affect developers. Firefox 142 is the current Nightly version of Firefox and ships on August 19, 2025.

Note: The release notes for this Firefox version are still a work in progress.

Changes for web developers

Experimental web features

These features are shipping in Firefox 142 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.

Older versions