.jxl

What is a .jxl file?

JPEG XL is a next-generation image format designed to replace both JPEG and PNG with superior compression.

Safe format
Type Image
By JPEG Committee (ISO/IEC)
MIME image/jxl

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What is it

JPEG XL is the format the imaging world has been waiting for. It compresses photos 20-60% better than JPEG at the same quality, supports lossless compression (replacing PNG), handles transparency, animation, HDR, and wide colour gamut — all in one format. It can even losslessly recompress existing JPEG files to 20% smaller, then reconstruct the original JPEG bit-for-bit. No other format does this.

The technical pedigree is impeccable: it combines Google's PIK research with Cloudinary's FUIF format, standardised by the JPEG committee as the official successor to JPEG. Progressive decoding means images appear quickly at low quality then sharpen, exactly like progressive JPEG but better.

The adoption story is more complicated. Chrome added then removed JPEG XL support (controversially). Safari supports it. Firefox is working on it. The format's future depends on browser adoption. For now, it's used in photography workflows (darktable, RawTherapee), image archives, and by early-adopter CDNs. If browsers fully adopt it, JPEG XL could genuinely replace JPEG, PNG, and GIF in one format.

Technical details
Full Name
JPEG XL
MIME Type
image/jxl
Developer
JPEG Committee (ISO/IEC)
Magic Bytes
FF 0A
Safety
.jxl is a known, safe format. Image data only. No executable content.
What opens it
Safari
FREE Mac / iOS
GIMP (2.10.32+)
FREE Windows / Mac / Linux
darktable
FREE Windows / Mac / Linux
FAQ
Is JPEG XL better than WebP?
Technically yes — JPEG XL offers better compression, supports lossless and lossy modes, handles HDR, and can losslessly recompress existing JPEGs. But WebP has universal browser support while JPEG XL adoption is still incomplete.
Will JPEG XL replace JPEG?
It's designed to, and it's technically superior in every way. But adoption depends on browser support, which is currently inconsistent. Safari supports it; Chrome removed it; Firefox is evaluating. The format's future is uncertain.
Can JPEG XL really recompress JPEG without quality loss?
Yes. JPEG XL can losslessly transcode an existing JPEG file to ~20% smaller, then reconstruct the original JPEG bit-for-bit. This is a unique feature no other format offers.
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