About JPEG XL
JPEG XL is the format the JPEG committee itself designed to replace JPEG, standardized by ISO in 2022. It compresses better than JPEG in lossy mode, better than PNG in lossless mode, and supports HDR, wide color gamuts, high bit depths, and enormous image dimensions.
Its most distinctive trick is lossless JPEG recompression: an existing JPEG can be repacked as JPEG XL roughly 20% smaller with zero quality loss, then converted back to the byte-identical original at any time. No other modern format offers that migration path for the billions of JPEGs already in the world.
The catch is adoption. Among browsers, only Safari currently displays JPEG XL, and Chrome removed its experimental support — so it is not yet safe for general web publishing. Convertmaxxing encodes and decodes JPEG XL directly in your browser: convert your images to .jxl to experiment or archive, or convert .jxl files back to JPG or PNG so anyone can open them. Free, no signup, and files never leave your device.
Strengths
- Stronger compression than JPEG in lossy mode and PNG in lossless mode
- Recompresses existing JPEGs about 20% smaller with no quality loss — reversibly
- Supports HDR, wide gamut, high bit depths, and progressive decoding
- Encodes much faster than AVIF at comparable quality
Limitations
- Browser support is limited — currently only Safari displays JPEG XL
- Chrome dropped its support, which has stalled adoption across the web
- Most upload forms, chat apps, and older editors will not accept .jxl files
Two codecs in one format
JPEG XL is unusual in carrying two distinct compression engines under a single wrapper. For photographic content it uses a transform-based mode descended from Google’s PIK project, with perceptual tuning aimed at how the eye actually judges error rather than at raw mathematical difference. For non-photographic content — screenshots, line art, anything with flat regions and hard edges — it switches to a modular mode derived from FUIF, which behaves much more like a very good lossless coder.
This is why JPEG XL avoids the usual trade-off where a format is excellent at photos and mediocre at graphics, or the reverse. It does not have to pick: the encoder chooses the appropriate mode, and can even apply different modes to different regions. It also decodes progressively, so a partially downloaded file renders as a complete but lower-resolution image rather than the top few rows.
The adoption problem, stated plainly
By most technical measures JPEG XL is the strongest general-purpose still-image format available, and it is nonetheless the one you should be most careful about using. Chrome shipped it behind a flag, then removed the code entirely in 2023, citing insufficient ecosystem interest. Safari added support in 2023. Firefox has an implementation available but not enabled by default. The result is a format that a large fraction of your audience cannot see.
That makes JPEG XL a reasonable choice for personal archives, where you control what opens the files and the lossless JPEG recompression is genuinely valuable, and a poor choice for anything you publish or send to other people. If you have .jxl files you need to share, converting them to JPEG or PNG is the practical move — and if you are archiving, remember that the JPEG recompression path is reversible, so nothing is locked in.
Frequently asked questions
- Can I use JPEG XL on my website?
- Not safely as your only format. Safari displays JPEG XL, but Chrome removed support and Firefox does not enable it by default, which means a large share of visitors would see nothing. If you want to experiment, serve it through a picture element with a JPEG or WebP fallback so unsupported browsers still get an image.
- What is lossless JPEG recompression?
- JPEG XL can repack an existing JPEG into a smaller file — typically around 20% smaller — without decoding and re-encoding the image. Because the original JPEG data is preserved rather than reprocessed, the operation is fully reversible: converting back produces the original file, not merely something that looks like it. It is the only credible way to shrink a large JPEG archive without any quality cost.
- Is JPEG XL better than AVIF?
- They win on different axes. JPEG XL encodes considerably faster, handles lossless and non-photographic content far better, and offers the JPEG recompression path. AVIF usually edges it out on lossy compression at low quality settings, and — decisively — it has real browser support today. On technical merit JPEG XL is arguably ahead; on practical usability AVIF wins.
- How do I open a .jxl file someone sent me?
- Safari will display it directly. Elsewhere, most software will not open it, and the simplest fix is to convert it to JPEG or PNG — which you can do on this page, in your browser, without uploading the file anywhere.