AVIF to JXL Converter
Convert AVIF to JXL in your browser. AVIF files usually come from image CDNs, modern web build pipelines and some recent phones; JXL is the better fit for archiving and future-proof high quality storage. You get a JPEG XL encoded with libjxl compiled to WebAssembly, lossy at the quality you choose or lossless. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
AVIF expected · other image formats also work
How to use AVIF to JXL
- 1
Add your AVIF files: drop them here, choose them, or paste from the clipboard.
- 2
Set the quality.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .jxl files one at a time or together as a ZIP.
Why use Aback Images for avif to jxl
Where the JXL goes next
JXL opens in Safari 17+, macOS 14 and iOS 17, GIMP, Krita, ImageMagick and the libjxl tools.
JXL next to AVIF
Both formats are lossy, so the size mostly follows the quality setting; at the default the JXL usually lands in the same range as the AVIF.
A second lossy pass
AVIF is lossy already, since it stores lossy or lossless AV1 intra-frame coding, so keep the quality at or above the default to avoid stacking a new layer of artefacts on the old one.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
AVIF vs JXL
What changes from AVIF to JXL
Encoding: the AVIF uses lossy or lossless AV1 intra-frame coding; JXL uses lossy VarDCT or lossless modular coding; existing JPEGs can be repacked without loss, and the download is a JPEG XL encoded with libjxl compiled to WebAssembly, lossy at the quality you choose or lossless.
Bit depth: 8, 10 or 12 bits per channel in the AVIF; JXL allows 8 to 16 bits per channel, or floating point, and the JXL written here has 8 bits per channel. 10 and 12-bit AVIFs, including HDR ones, are decoded to 8 bits per channel.
Colour: YUV 4:4:4 or 4:2:0 with BT.709, Display P3 or BT.2020 primaries, HDR curves possible in the AVIF; JXL supports sRGB, Display P3, linear and other spaces described in the codestream, written here as 8-bit sRGB.
Transparency: the AVIF stores it as an auxiliary AV1 image stored beside the colour image; the JXL keeps it as an extra channel in the codestream.
Animation: an AV1 image sequence under the 'avis' brand; the JXL holds one image, so only the first frame is converted.
Metadata: the AVIF can carry EXIF, XMP and ICC stored as HEIF items; JXL can carry EXIF and XMP boxes in the container form, often stripped by encoders, but nothing is copied across.
About AVIF
AVIF uses the AV1 video codec for still images. It is the most efficient widely supported format, often half the size of JPEG, with HDR, wide colour and transparency, but encoding is slow.
An AVIF is a HEIF file, the same ISO base media boxes as MP4, with the brand 'avif'. The picture is an AV1 key frame stored as an image item, and its size, colour and pixel layout are item properties.
AVIF files usually come from image CDNs, modern web build pipelines and some recent phones.
About JXL
JPEG XL is a next-generation format designed to replace JPEG. It compresses better than JPEG and WebP, supports lossless, HDR and progressive decoding, and can losslessly repack existing JPEGs.
A JPEG XL file is either a bare codestream starting with FF 0A or an ISO base media container whose 'jxlc' box holds the codestream. A recompressed JPEG keeps a 'jbrd' box that lets the original JPEG bytes be rebuilt exactly.
When converting AVIF to JXL makes sense
JXL is the better choice for archiving and future-proof high quality storage, while AVIF suits maximum compression on modern websites.
JXL strengths: Excellent lossy and lossless compression; Progressive decoding and HDR; Huge image sizes. Drawbacks to weigh: Browser support is limited (Safari only by default); Few apps can open it yet.
Limitations
- Almost any other format needs more bytes than AVIF for the same picture, so expect the file to grow.
- HDR and wide-gamut AVIFs are mapped to standard sRGB on decode, so very bright highlights can look flatter than on an HDR screen.
- Chrome and Firefox do not display JPEG XL by default, so it is not yet a format for websites; it suits archives and apps that support it.
- Lossless JPEG XL is usually smaller than PNG for the same pixels.
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Frequently asked questions
Does converting AVIF to JXL lose quality?
JXL is lossy, so detail the eye barely notices is discarded to save space. The AVIF was lossy already, so keep the quality high to avoid stacking artefacts. 10 and 12-bit AVIFs, including HDR ones, are decoded to 8 bits per channel.
Is transparency kept in the JXL?
Yes. AVIF stores it as an auxiliary AV1 image stored beside the colour image, and the JXL is written with an alpha channel, so transparent areas stay transparent.
Will my animated AVIF stay animated?
No. JXL holds a single image, so only the first frame is kept. Convert to animated WebP, APNG or GIF to keep the motion, or export every frame with the GIF Frame Extractor.
Which apps open JXL files?
Safari 17+, macOS 14 and iOS 17, GIMP, Krita, ImageMagick and the libjxl tools. It opens in Safari 17 and later; Chrome and Firefox do not display it by default.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.