Mozilla Firefox 139 Beta improves PNG support, HTTP/3 performnace & more

Yesterday, Mozilla released Firefox version 138 in the Release channels with some neat features, including Tab Groups and profile manager. The company also dropped the Firefox 139 Beta alongside. Fortunately, it’s got some cool updates that would make browsing smoother and smarter.

Mozilla releases Firefox 139 Beta with a few expected improvements

If you’ve ever uploaded big files and felt like it took forever, Firefox 139 Beta has got your back. It improves HTTP/3 upload performance, especially for resumed connections (QUIC 0-RTT) and high bandwidths and high-delay networks.

In short, the Firefox 139 Beta update ensures that your uploads should feel snappier when sharing videos or big files. If you ever felt like translating an entire Firefox extension page, now you can. The latest beta update adds support for the same, making you easily understand content in other languages.

If you’ve ever copied and pasted a PNG image into Firefox and noticed the transparent background turned weird, this update fixes that. Firefox 139 Beta now preserves PNG transparency, so your images look clean and professional when you paste them.

The stable version will drop next month

Mozilla says that Firefox 139 Beta is available now for testing, but it’s not the final version—don’t use it for critical work just yet. The full release is set for May 27, 2025, alongside some other Firefox updates. You can download the beta from Mozilla’s official site if you want to try it out.