Firefox 157 Ships JPEG XL by Default

Mozilla's Timothy Nikkel posted the intent-to-ship JPEG XL decoding by default on the dev-platform group on Monday. Firefox 157 will enable the format on all platforms — Nightly, Beta, and Release — with no flag needed.

This is the final step after nearly two years of development behind image.jxl.enabled, a Firefox Labs checkbox since version 152, and a rewrite around the Rust-native jxl-rs decoder. The performance concern that held it back (raised during the intent-to-prototype phase) has been resolved: jxl-rs 0.6.0 shipped multithreaded decoding, Mozilla's integration patches are landing, and the benchmarks cleared the bar.

Why this matters. JPEG XL is the only next-gen image format that doesn't force a tradeoff. It compresses ~60% better than legacy JPEG, supports lossless re-encoding of existing JPEGs with zero quality loss (progressive decoding included), wide gamut, HDR, and animation — all in a single container. Unlike WebP or AVIF, it's designed to replace JPEG, not compete alongside it.

The browser landscape is now asymmetric: Safari shipped JPEG XL in Safari 17.0 back in 2023. Chrome sits on the sidelines — it has JPEG XL behind #enable-jxl-image-format (using the same Rust library) but has shown no intent to ship. That means the two browser engines with the format enabled (WebKit and Gecko) cover iOS/iPadOS and a growing share of desktop, while Chromium remains the holdout.

For web developers, the calculus shifts: JPEG XL becomes practical for sites where Safari + Firefox dominate traffic. Image CDNs and optimizers should start treating it as a real delivery option, not a speculative flag.

The format war never really ended — it just quietly entered a new phase.