JPEG XL Finally Gains Cross‑Browser Support in Firefox and Chrome

After years of intermittent interest and a previous removal that annoyed developers, JPEG XL is finally being rolled out for widespread use. Firefox will enable default JPEG XL decoding in version 157 (users could already test the feature in version 152), and Chrome has announced its intention to make the decoder default as well, making cross‑browser support possible by the end of the year.

A key factor in this progress is the Rust‑based decoder jxl‑rs developed by Google’s research team. Mozilla challenged Google to prove the safety of a JPEG XL decoder; the original C++ implementation contained about 100,000 lines of code and raised memory‑safety concerns when handling untrusted images. Re‑implementing the decoder in Rust eliminated those safety issues.

One notable detail is that the Rust decoder supports progressive rendering, whereas Safari’s current JPEG XL implementation (written in C++) does not. Consequently, even among browsers that support the format, functional differences remain.

Mozilla’s documentation also compares JPEG XL with AVIF and states that there is no clear winner; the choice depends on the specific use case. For lossless images, JPEG XL often delivers better performance. It also provides superior progressive rendering, which can improve page‑load speed on slow connections. For typical lossy, web‑quality images, the trade‑offs are discussed but depend on the scenario.

Safari added JPEG‑XL support in 2023, but it uses the older C++ implementation rather than the Rust version.

For lossless images, JPEG XL usually outperforms AVIF in speed and compression.

JPEG XL’s progressive rendering can significantly improve loading times on slow networks.

Typical lossy, web‑quality images are evaluated case‑by‑case, with no definitive superiority.

References: https://groups.google.com/a/mozilla.org/g/dev-platform/c/3YMV4MS34KA/m/iqfJV5cXEQAJ?pli=1 https://groups.google.com/a/chromium.org/g/blink-dev/c/-gDojQbDPRI https://zh.wikipedia.org/wiki/JPEG_XL