Firefox news — Web Standards

May 19
Firefox 151 release notes for developers
@container style() queries, Document Picture-in-Picture, desktop Web Serial, and keyboardLock.
May 15
Browsers treat big sites differently
How Safari and Firefox quietly patch the web to keep big sites working.
April 21
Firefox 150 release notes for developers
New CSS features, media pseudo-classes, animation range, and ariaNotify().
March 24
Firefox 149 release notes for developers
Popover hint, CloseWatcher, shape-outside: xywh(), and more CSS and API updates.
February 27
Making WebAssembly a first-class language on the web
Component model could remove JS glue, simplify loading, and speed up web API access.
February 25
Firefox 148 release notes for developers
HTML sanitizer, Trusted Types, CSS shape(), and more.
January 14
Firefox 147 release notes for developers
CSS anchor positioning, Navigation API, WebGPU on Apple Silicon, and DevTools improvements.
December 10, 2025
Firefox 146 release notes for developers
CSS and MathML improvements plus new APIs and Navigation API preview.
November 12, 2025
Firefox 145 release notes for developers
New CSS, JS and media features plus experimental security and layout APIs.
October 16, 2025
What’s new in Firefox 144 for developers
View Transitions in SPAs, command/commandfor attributes, getOrInsert(), and moveBefore().
September 18, 2025
What’s new in Firefox 143 for developers
New color formats in color input, ::details-content, ::before::marker, and grid improvements.