Firefox 157 to Enable JPEG XL Decoding by Default Across All Platforms

Mozilla is set to enable JPEG XL decoding by default on all platforms starting with Firefox 157. The move transitions the modern image format from an experimental feature to a standard browser capability.

Mozilla engineer Timothy Nikkel announced the intent to ship the feature, which utilizes the Rust-based jxl-rs decoder. While the functionality has been available to early adopters via Firefox Nightly and Firefox Labs since version 152, the upcoming release will make the format accessible to the entire user base without manual configuration.

The Push for Modern Compression

JPEG XL (ISO/IEC 18181) is designed as a comprehensive successor to the aging JPEG standard. It offers superior compression efficiency and supports both lossy and lossless modes, allowing web developers to reduce file sizes without sacrificing visual quality. To ensure stability and performance before this full rollout, Mozilla has spent months prototyping the format and testing it through the 'image.jxl.enabled' flag.

Firefox's implementation includes support for animation and progressive display, allowing images to load in stages rather than appearing as a single block. This adds a layer of versatility for developers looking to optimize the user experience on slower connections.

A Fragmented Browser Landscape

The rollout highlights a continuing divide in how major browser vendors approach image standards. Apple's Safari was an early adopter, shipping JPEG XL support in version 17.0 in 2023. In contrast, Google Chrome has kept the format behind a feature flag and has expressed no current intent to enable it by default for its users.

By enabling the format by default, Firefox puts additional pressure on other vendors to standardize. For the broader web ecosystem, the adoption of JPEG XL provides a more efficient alternative to WebP and traditional JPEGs, particularly for high-dynamic-range (HDR) content and advanced tone mapping for SDR displays.

What to Watch

As Firefox 157 approaches, the industry will be watching to see if Chrome follows suit to avoid a fragmented web where high-efficiency images only render in a subset of browsers. While the core decoding is confirmed, the long-term impact on mobile battery life and the exact performance trade-offs compared to WebP remain points of internal discussion among engineers.