JPEG XL Converter — Free, Fast & Private
This page converts to JPEG XL and from it. Most browsers still cannot display a .jxl, which shapes what you should do with the file. Everything runs in your browser — nothing is uploaded.
Display support is the constraint
Safari has decoded JPEG XL since version 17; Chrome and Firefox keep support behind flags that are off by default. That is why the tool shows the preview and before-and-after comparison itself, through its own decoder. A .jxl made here suits archives and pipelines that support it; for pages every visitor can see, use WebP or AVIF through the AVIF compressor.
Lossless at quality 100
The encoder is libjxl compiled to WebAssembly and downloaded the first time you pick JXL (1.3 MB). The slider maps onto libjxl's own scale, and 100 is lossless: every pixel is kept. JXL is never chosen by Auto, because most browsers cannot open the result; you must select it.
It re-encodes pixels, not JPEG data
JPEG XL can rewrap an existing JPEG losslessly and reversibly. This tool does not: it works from decoded pixels, so a JPEG dropped here is a new encode. For bit-exact reversibility use the command-line JXL tools.
Converting from .jxl
Drop a .jxl and switch the format pill to JPEG, PNG, WebP or AVIF. Decoding uses the bundled decoder, so it works in Chrome and Firefox too. Format comparison: WebP vs AVIF vs JXL.
Check the JPEG XL before you save
The result card shows the original size, the .jxl size and the output dimensions, with a before and after slider decoded by the page itself. Batches download as a ZIP.
Speed and size limits
The encoder runs single-threaded, so large photos take longer, and very large frames are scaled to a 64-megapixel ceiling with a note. If the encoder cannot download, the tool keeps your original and says so.
JPEG XL on real files: measured sizes
| File | Before | After | Change | Background |
|---|---|---|---|---|
| 12 MP phone photo | JPG · 4032 × 3024 px · 3.73 MB | JPEG XL · 4032 × 3024 px · 1.07 MB | 3.5× smaller | — |
| Screenshot (PNG) | PNG · 1280 × 800 px · 88.1 KB | JPEG XL · 1280 × 800 px · 32.5 KB | 2.7× smaller | — |
| App icon on transparency (PNG) | PNG · 2048 × 2048 px · 162.5 KB | JPEG XL · 2048 × 2048 px · 50.4 KB | 3.2× smaller | — |
Measured 2026-10-07 in Chromium 145.0.7632.6 by running this page's converter with its default setting (JPEG XL) on each file. The photos and scans are CC0 or public-domain files from Wikimedia Commons; the screenshot is MiniPx's own; the app icon is drawn by the measuring script, with a soft shadow so partial transparency is tested. Sizes are shown as the tool shows them (1 KB = 1,024 bytes).