What Is JPEG XL? Format Guide for Web Developers

JPEG XL is a next-generation image format that offers excellent compression, lossless and lossy modes, progressive decoding, and lossless transcoding from existing JPEG files.

What is JPEG XL?

JPEG XL (file extension .jxl) was standardized as ISO 18181 in 2022. It was designed by the Joint Photographic Experts Group as a modern replacement for JPEG that addresses the limitations of both JPEG and newer formats like WebP.

Key features of JPEG XL:

• Lossy and lossless compression. Both modes in one format. Lossy compression is competitive with AVIF. Lossless compression is better than PNG.
• Progressive decoding. Images load in increasing quality, similar to progressive JPEG but more efficient. Users see a usable preview almost immediately.
• Lossless JPEG transcoding. Convert an existing JPEG to JPEG XL and back to an identical JPEG with zero quality loss. The JXL version is typically 20% smaller. No other format can do this.
• HDR and wide color gamut. Full support for modern display capabilities.
• Fast encoding and decoding. Significantly faster than AVIF encoding, comparable to WebP.

How does JPEG XL compare to AVIF and WebP?

Feature	JPEG XL	AVIF	WebP
Lossy compression	Excellent	Excellent	Good
Lossless compression	Excellent	Good	Good
Progressive decoding	Yes (native)	No	No
Lossless JPEG transcoding	Yes	No	No
Encoding speed	Fast	Slow	Fast
Browser support (2026)	Safari, partial others	Universal (95%+)	Universal (99%+)
HDR support	Yes	Yes	No
Animation	Yes	Yes	Yes
Max dimensions	Unlimited (terapixel)	8K (with tiling)	16,383 x 16,383

On pure compression, JPEG XL and AVIF are close, with each winning on different content types. JPEG XL tends to do better on photographic content at high quality settings. AVIF tends to do better at lower quality settings and on content with complex textures.

JPEG XL’s unique advantages are progressive decoding (useful for large hero images) and lossless JPEG transcoding (useful for archival and migration workflows). No other format offers either feature.

Which browsers support JPEG XL?

Browser support for JPEG XL is mixed as of 2026:

• Safari: Full support since Safari 17 (2023). All Apple devices with recent OS updates support JPEG XL natively.
• Chrome: Removed built-in support in Chrome 110 (2023), citing lack of ecosystem momentum. Available behind a flag. There is ongoing discussion about re-adding support.
• Firefox: Partial support behind a flag (image.jxl.enabled in about:config). Not enabled by default.
• Edge: Follows Chrome (removed).

This means JPEG XL is not yet a universal web format. You cannot serve JPEG XL as your only format and expect all users to see it. But you can serve it as an additional source in a <picture> element for browsers that support it, with AVIF or WebP as the fallback.

How do you serve JPEG XL with Small Pics?

Small Pics is one of very few image transform services that supports JPEG XL output. Use the fm=jxl parameter:

https://your-domain.smallpics.io/photo.jpg?w=800&fm=jxl

To serve JPEG XL with fallbacks for broader support:

<picture>
  <source srcset="https://your-domain.smallpics.io/photo.jpg?w=800&fm=jxl" type="image/jxl" />
  <source srcset="https://your-domain.smallpics.io/photo.jpg?w=800&fm=avif" type="image/avif" />
  <img src="https://your-domain.smallpics.io/photo.jpg?w=800&fm=webp" alt="Photo" loading="lazy" />
</picture>

Safari users get JPEG XL with progressive decoding. Everyone else gets AVIF (or WebP as the final fallback). One URL pattern, three formats, zero server-side logic.

As of March 2026, only Small Pics and Gumlet support JPEG XL output among the major image transform services.

Should you use JPEG XL in production?

It depends on your audience and priorities.

Use JPEG XL if:

• A significant portion of your traffic is Safari/Apple users (common for consumer-facing sites)
• You want progressive decoding for large hero images
• You are building a multi-format <picture> pipeline anyway and adding one more source is free
• You want to future-proof your image stack

Stick with AVIF + WebP if:

• You want the simplest possible setup
• Your audience is primarily Chrome/Android users
• You do not want to manage a third format variant

For most sites, the practical recommendation in 2026 is to default to AVIF (which Small Pics does automatically) and add JPEG XL as a bonus for Safari users if your tooling supports it. Small Pics and Gumlet are currently the only major image transform services that support JPEG XL output.