What Is JPEG XL (JXL)? The Complete Guide

What is JPEG XL?

JPEG XL (file extension .jxl) is an open, royalty-free image format standardised by the Joint Photographic Experts Group — the same body behind the original JPEG. The specification was finalised in 2022 (ISO/IEC 18181).

The name "XL" signals two goals: eXtra Large quality at a given file size, and a Long-term replacement for legacy JPEG. The format is designed to handle everything from tiny thumbnails to high-resolution professional photographs, including HDR content, animation, and lossless archival copies.

One of JXL's most practical features is lossless JPEG transcoding. An existing JPEG can be re-encoded into JXL with zero quality loss and an average file-size reduction of around 20%, then decoded back to the identical original JPEG bytes — making it a compelling archival upgrade path for billions of existing photos.

Key advantages of JXL

Superior compression

At equivalent visual quality, JXL produces files roughly 35–60% smaller than legacy JPEG and meaningfully smaller than WebP at medium-to-high quality settings. For high-resolution images on slow mobile connections this translates directly into faster load times and lower bandwidth costs.

True lossless compression

JXL's lossless mode is competitive with PNG — often 5–10% smaller — and supports the same full 32-bit RGBA colour depth. This makes it suitable as a master format for graphics, screenshots, and design assets where pixel-perfect fidelity is required.

HDR and wide colour gamut

The format natively supports up to 32 bits per channel, HDR (PQ and HLG transfer functions), and wide colour gamuts including Display P3 and Rec. 2020. As HDR displays become mainstream, JXL is positioned to carry forward the same role JPEG played for SDR photography.

Progressive decoding

JXL supports a responsive progressive mode that lets browsers render a low-resolution preview almost instantly, then fill in detail as more data arrives. Unlike progressive JPEG, this mode is designed to work efficiently with modern streaming HTTP delivery.

Animation

Animated JXL sequences are lossy- or lossless-compressed and can contain thousands of frames — far beyond what GIF's 256-colour palette allows, and without the royalty concerns that historically surrounded video codecs.

Browser support status (2026)

JXL adoption has been uneven, but momentum is building as of mid-2026.

• Firefox: Full support landed in Firefox 152 (shipped June 2026). This is the most significant recent change in JXL adoption — Firefox has a large desktop user base and its support removes a major barrier for web deployment.
• Safari: Support has been present since Safari 17 (macOS Sonoma / iOS 17, 2023). Apple Photos and Preview also open JXL files natively on macOS 14+.
• Chrome / Edge: Available behind the enable-jxl flag in chrome://flags but not yet enabled by default. Google removed default support in 2023 citing insufficient adoption data, though the flag remains available for testing.
• Chromium-based browsers (Brave, Opera, Arc): Follow Chrome's flag behaviour; some ship with it enabled by default.

For production web delivery you should still provide a JPEG or WebP fallback using the HTML <picture> element with a type="image/jxl" source until Chrome enables support unconditionally.

How to open and convert JXL files

Online converter (no software needed)

The easiest way to open a JXL file on any device is to use our free JXL Converter. Drop your .jxl file into the tool and it converts to JPG or PNG entirely in your browser — no upload, no account, no waiting. The same tool converts JPG and PNG to JXL so you can create and experiment with the format immediately.

Desktop applications

• macOS Preview and Photos — native support on macOS 14 (Sonoma) and later.
• GIMP 3.0+ — open-source image editor with JXL import/export via the libjxl plugin.
• Darktable — photography workflow software with JXL support built in.
• ImageMagick 7.1+ — command-line tool supporting batch JXL conversion on Linux, macOS, and Windows.
• Windows Photos — requires the JPEG XL Image Extension from the Microsoft Store.

Command-line (libjxl)

The reference implementation ships the djxl (decode) and cjxl (encode) command-line tools. They are available via Homebrew (brew install jpeg-xl) on macOS and most Linux package managers.

JXL vs WebP vs AVIF

All three formats aim to replace JPEG for web delivery, but they make different trade-offs. The table below summarises the main differences at a glance.

In summary: JXL has the best technical specification of the three, but WebP and AVIF have broader browser defaults today. Once Chrome enables JXL by default, it is likely to become the preferred format for most web images.

FAQ

Is JXL the same as JPEG?

No. Despite sharing the "JPEG" name, JXL is an entirely new format with a different bitstream, codec, and file extension (.jxl). Legacy JPEG (.jpg) and JPEG XL are not interchangeable without conversion.

Can I use JXL on my website today?

Yes, with a fallback. Use the HTML <picture> element to serve JXL to browsers that support it (Safari, Firefox 152+) and fall back to WebP or JPEG for Chrome users. This gives you the file-size savings where available without breaking anything.

Is JPEG XL royalty-free?

Yes. The JPEG XL specification is royalty-free. The reference implementation (libjxl) is released under a BSD-3-Clause licence, making it suitable for both open source and commercial use.

Does JXL support transparency?

Yes. JXL supports an alpha channel in both lossy and lossless modes, making it a capable replacement for PNG in use-cases requiring transparency.

How do I convert JXL to JPG right now?

Use the free online JXL Converter on this site. It runs entirely in your browser via WebAssembly — no file is ever uploaded to a server — and takes only a few seconds per image.