Firefox for Web Developers

Official Firefox account for people who build on the web. Learn about the things we're working on to grow and improve the web platform.

[Firefox for Web Developers @FirefoxWebDevs]

Firefox 159 has landed! This is a pretty big one for web dev stuff:

🎉 CSS scroll-driven animations, both scroll() and view().
🎉 Scoped custom element registries.
🎉 Streaming sanitization of HTML.

And more! https://t.co/PKkzsfKlrW

[Firefox for Web Developers @FirefoxWebDevs]

@ArmEagle They are farrrrrr worse. There's one comparison in the video to JPEG - the AVIF is 60% smaller.

[Firefox for Web Developers @FirefoxWebDevs]

JPEG XL is newly available in all major engines, but how does it stack up against other formats?

[Firefox for Web Developers @FirefoxWebDevs]

What should we ship in 2027? Rank your favourite features & create your wishlist: https://t.co/xDo2xRpTRQ

[Firefox for Web Developers @FirefoxWebDevs]

@monstercameron Hah! Firefox releases are every two weeks now.

[Firefox for Web Developers @FirefoxWebDevs]

Firefox 158 landed today! For web devs:

🎉 JPEG XL support, including full progressive rendering.
🎉 'navigate' on notifications, so they can go to a URL without firing events.
🎉 WebGPU's float32-blendable
🎉 WebGL's EXT_polygon_offset_clamp

And more!

https://t.co/P2JhyGZHEO

[Firefox for Web Developers @FirefoxWebDevs]

@adityareddydev You can test it at https://t.co/JRR7xWv7I0

[Firefox for Web Developers @FirefoxWebDevs]

We've loved seeing folks post their rankings, so we've added a share button!

You can either share your list via the site directly, or copy your list as markdown/html for your own blog.

https://t.co/xDo2xRpTRQ

[Firefox for Web Developers @FirefoxWebDevs]

@sawani_sid94949 We look at the data a number of different ways, but the primary way is https://t.co/mJXsxmSNd2

[Firefox for Web Developers @FirefoxWebDevs]

What do you want us to work on in 2027?

Here's a web app where you can rank the Interop proposals you care about, giving us data we can use to prioritise feature development.

https://t.co/xDo2xRpTRQ

[Firefox for Web Developers @FirefoxWebDevs]

@SKOLZZ Ah, this is specifically about the remaining test failures. I'll update the text on the site.

[Firefox for Web Developers @FirefoxWebDevs]

@SKOLZZ Good catch. Although this project isn't just about Firefox features (Interop is a cross-browser project), sibling-index() has shipped across engines. I've proposed closing this, which would also remove it from the site https://t.co/xVhGwevF7K

[Firefox for Web Developers @FirefoxWebDevs]

We ran this last year to decide what to champion for Interop 2026, but the data was so good, we also used it to prioritise features beyond the Interop project.

We've also added some features to make it quicker to rank items.

[Firefox for Web Developers @FirefoxWebDevs]

@Maduemezia90188 @supports Can you give me more details? Eg, links to demos that aren't behaving as expected

[Firefox for Web Developers @FirefoxWebDevs]

Firefox 157 has landed, and includes a couple of useful CSS features:

🎉 at-rule() in @supports - limit rules to browsers that support a given at-rule.
🎉 overscroll-behavior: chain - allow chained scrolling without overscroll effects.

…And more! https://t.co/t3M1vyEYqB

[Firefox for Web Developers @FirefoxWebDevs]

@siddharthverse @firefox Can you give us a link an entry in about:crashes showing this crash?

[Firefox for Web Developers @FirefoxWebDevs]

@siddharthverse @firefox Thanks for letting us know. Looking into it…

[Firefox for Web Developers @FirefoxWebDevs]

@ildella @firefox @firefoxbeta Thank you! I'll raise this with the team

[Firefox for Web Developers @FirefoxWebDevs]

When and how CSS custom property values are calculated might not be what you expect, and it has a big impact on your styles…