Integrating JPEG XL in Chromium with jxl-rs

Why Chromium selected a Rust decoder, how it was integrated, and how it reached default enablement.

Status: ✅ Enabled by Default in Chrome 155

The Story

In October 2022, Google removed JPEG XL from Chromium, citing "insufficient ecosystem interest."

In November 2025, Chrome's Architecture Tech Leads announced: "We would welcome contributions to integrate a performant and memory-safe JPEG XL decoder in Chromium."

What changed?

• Safari shipped JPEG XL — Apple implemented the format
• Firefox updated their position — Mozilla signaled support pending a Rust decoder
• PDF standardization — JPEG XL designated as the preferred format for HDR in PDF
• Developer demand — Bug upvotes, Interop proposals, and survey data

Why JPEG XL?

• 30-50% better compression than JPEG at equivalent quality
• Lossless JPEG transcoding with ~20% size reduction
• Progressive decoding — images load incrementally
• Modern capabilities — HDR, wide gamut, alpha, animations
• Cross-browser momentum — Safari ships it, Firefox is working on it

Implementation

Phase 1: C++ (Abandoned)

Initial approach used libjxl in C++. Feature complete with animation support, but feedback requested Rust for memory safety.

ABANDONED CL 7170439 — C++ implementation (superseded by Rust)

Phase 2: Rust (Current)

Pivoted to jxl-rs, a pure Rust decoder. Memory-safe and aligned with Chromium's direction.

MERGED CL 7201443 - Add jxl-rs to third_party

Blink integration:

1. MERGED CL 7320482 — Add JXL infrastructure: enums and build flag
2. MERGED CL 7319379 — Add JXL image decoder using jxl-rs
3. MERGED CL 7184969 - Wire up the JXL decoder

The Rust decoder also needed performance work for browser workloads. Representative measurements from that period:

Current Status

✅ Standard image decoding
✅ ICC color profiles
✅ Animations (multi-frame)
✅ Alpha/transparency
✅ Wide gamut (Display-P3)
✅ HDR support (PQ/HLG)

Chromium rolls:

• MERGED Roll jxl 0.2.1 → 0.2.2
• MERGED Roll jxl 0.2.0 → 0.2.1
• MERGED Roll jxl 0.1.5 → 0.2.0

Testing Without Native Support

The jxl-rs-polyfill provides a WASM fallback for testing JPEG XL on browsers without native decoding.

Basic usage:

<script src="https://cdn.jsdelivr.net/npm/jxl-rs-polyfill/dist/auto.js"></script>

The script detects native support before installing its fallback. It covers common <img>, CSS background, <picture>, and SVG cases; the WASM payload is approximately 540 KB gzipped.

npm install jxl-rs-polyfill

import { JXLPolyfill } from 'jxl-rs-polyfill';
const polyfill = new JXLPolyfill();
await polyfill.start();

import { decodeJxlToPng } from 'jxl-rs-polyfill';
const pngBytes = await decodeJxlToPng(jxlBytes);

→ GitHub: jxl-rs-polyfill

Live Demo

JXL animation support — no browser supports JXL animations natively yet, so this uses the WASM polyfill:

Force Polyfill (See Animation)

Acknowledgments

Special thanks to Luca Versari (veluca93) for reviewing PRs and managing jxl-rs releases. The collaboration from jxl-rs maintainers made this possible.

Resources:

• JPEG XL, One Year Later: default enablement and hardening
• Default-enable CL 8279712
• Rick Byers' Announcement
• Tracking Bug: 462919304
• Design Document
• jxl-rs Repository
• jxl-rs-polyfill
• Press: Heise | DevClass