What is a .jxl file?
JPEG XL Image · Image · JPEG committee · 2022
JPEG XL is a modern image format built to replace JPEG. It offers much better compression, supports lossless and lossy modes, transparency and animation, and can losslessly recompress existing JPEG files to save space.
What is a .jxl file used for?
JXL was designed to do everything older formats do, better: smaller files at the same quality, a lossless mode, high dynamic range and even progressive loading. It can repack a normal JPEG with no quality loss and about 20 percent smaller.
Adoption is the catch. Support is growing in image tools and some browsers, but it is not yet universal, so many people still convert JXL to JPEG or PNG for sharing.
What opens a .jxl file?
The .jxl format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- XnView MP
- GIMP (with plugin)
- IrfanView
macOS
- Preview (recent macOS)
- GIMP
- XnView MP
Linux
- GIMP
- ImageMagick
- gwenview
Web
- Browsers with JXL enabled
Open a .jxl file step by step
- Confirm the file really is a .jxl. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with XnView MP or GIMP (with plugin).
- On Mac, use Preview (recent macOS) or GIMP.
- On Linux, try GIMP or ImageMagick.
- Still stuck? Convert the .jxl to jpg, which opens more widely.
Why can't I open my .jxl file?
Almost always because no installed app understands JPEG XL. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .jxl at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .jxl file
You can convert a .jxl file to jpg, png, webp using a conversion tool or the export menu of an app that opens it.
What is the .jxl file signature (magic bytes)?
A .jxl file starts with the hex bytes 00 00 00 0C 4A 58 4C 20 0D 0A 87 0A, which read as ....JXL .... in ASCII. Programs identify JPEG XL by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for JPEG XL. For a full breakdown, see the JPEG XL file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 00 00 00 0C 4A 58 4C 20 0D 0A 87 0A | 0 | ....JXL .... | container form (JXL box) |
| FF 0A | 0 | - | raw codestream |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .jxl file?
JPEG XL is a modern image format built to replace JPEG. It offers much better compression, supports lossless and lossy modes, transparency and animation, and can losslessly recompress existing JPEG files to save space.
How do I open a JXL file?
Use an image tool with JXL support such as XnView MP or GIMP, or Preview on recent macOS. If nothing opens it, convert it to JPEG or PNG.
Is JPEG XL better than JPEG?
Technically yes: smaller files, a lossless mode, transparency and better quality. Its limit today is compatibility, since not every app and browser supports it yet.
What is the difference between JXL and AVIF?
Both are modern successors to JPEG. AVIF has wider browser support now; JXL excels at lossless and at recompressing existing JPEGs without quality loss.
Related formats
Sources
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