JXL file format: what it is and how to use it

JPEG XL is the would-be heir to JPEG: lossy and lossless in one format, progressive by design, with better compression than everything mainstream. Learn when to use it and what to choose instead.

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What is a JXL file?

A .jxl file is an image in JPEG XL, the ISO/IEC 18181 format finalized in 2022 to replace JPEG outright: lossy and lossless in one codec, progressive decoding by design, HDR and alpha, and a signature party trick: it can repackage an existing JPEG losslessly ~20% smaller. Compression beats WebP and rivals AVIF while decoding faster and scaling to professional color.

When should you use JXL?

  • Photographic archives: lossless mode that still compresses well.
  • JPEG migration: losslessly shrink entire JPEG libraries.
  • Progressive delivery: images that resolve gracefully as bytes arrive.

When is another format a better fit?

For the live web, support is the blocker, since browsers outside Safari have been slow, so WebP and AVIF serve users today. For universal delivery JPG remains the floor; for masters PNG/TIFF. JXL is the best format you mostly cannot ship yet.

The short version: JXL is the technically superior successor JPEG deserves, still waiting on browser support to matter.

How to open a JXL file

On Windows

Double-click the file, or open it with IrfanView.

On macOS

GIMP opens JXL files on macOS.

In your browser

Open JXL files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • GIMP
  • XnView
  • IrfanView
  • Browsers (flag/extension)

View or convert JXL files

A quick preview or a new format. No install, no upload.

View JXL files Preview and inspect JXL files Convert to JXL Turn files into JXL JXL to AVIF AV1 Image File Format JXL to WEBP WebP image JXL to JPG JPEG (Joint Photographic Experts Group) JXL to PNG Portable Network Graphics

JXL technical details

Full name
JPEG XL
Extensions
.jxl
MIME type
image/jxl
Magic bytes
FF 0A / 00 00 00 0C 4A 58 4C 20 (container)
Compression
Lossless or lossy
Developer
JPEG committee (ISO/IEC 18181)
Specification
jpeg.org

JXL questions, answered

How do I open a .jxl file?

Safari reads it natively; Chrome/Firefox need flags or extensions, and tools like libjxl's djxl, GIMP and ImageMagick decode it. dexrr displays and converts jxl files in your browser.

Can I convert JXL files online?

Yes, dexrr converts jxl locally in your browser: JXL to PNG for lossless use, JXL to JPG or JXL to WebP for delivery.

Is JXL better than AVIF?

Technically, often: comparable compression, faster decode, lossless JPEG repacking and smoother progressivity. In practice, AVIF has the browser support JXL still lacks.

Can JXL really shrink JPEGs without loss?

Yes, a lossless transcode mode re-packs JPEG's DCT data ~20% smaller, reversible bit-for-bit back to the original file.

Is the JXL format outdated?

No, finalized in 2022, it is the newest major image standard; its problem is adoption, not age.