JPEG XL, usually called JXL, is a modern image format designed to store photographs, artwork, and other images efficiently. It supports both lossy compression, which trades some detail for smaller files, and lossless compression, which keeps the image data exactly intact. This converter always creates a lossless JXL with distance 0 and uses JPEG XL effort 10, the highest standard encoder effort setting.
JPEG inputs use JPEG XL reconstruction, preserving the original JPEG data so the JPEG can be recovered exactly from the JXL. Other image formats are decoded to pixels and then encoded as pixel-lossless JXL; that preserves their decoded pixels but does not preserve source compression data.
Are my images public?
No. Converted images are not listed publicly or exposed through the live queue. Downloads require a private, randomly generated token held only by the submitting browser. The token is not stored in the database or included in job status, and the converted image is removed from memory and becomes unavailable after five minutes. Anyone you intentionally share the download token with could use it before it expires.
What image formats are supported?
You can convert PNG, JPEG, WebP, AVIF, GIF, BMP, DDS, EXR, HDR, ICO, PNM, QOI, TGA, and TIFF files. Animated GIFs are accepted, but only their first frame is converted; the animation is not preserved.
Are there size or time limits?
Uploads are limited to 25 MB and must finish uploading within 30 seconds. Each conversion has a five-minute time limit. Images are also limited to 20,000 × 20,000 pixels.
What does highest effort mean?
This converter uses JPEG XL effort 10, the highest standard encoder setting. Higher effort gives the encoder more time to search for better compression, which can produce a smaller lossless file depending on the image. It never changes the pixels or reduces quality, but it does make conversion slower than lower-effort settings.
What does “lossless” mean?
A lossless file decodes to the exact same pixels that were supplied to the encoder. Nothing is softened, changed, or discarded by the conversion. That makes lossless JXL useful for archiving, editing, and keeping a high-quality master without adding another generation of compression damage. It cannot restore detail that a lossy source already discarded.
When did JXL arrive?
JPEG XL was standardized and released as an image format in 2021. It was designed to improve on older formats while supporting both new workflows and lossless recompression of existing JPEG images. Tool and browser support has continued to vary by platform.
Why can a converted image be larger?
If you convert a lossy JPEG or lossy WebP to lossless JXL, the result will often be larger. The source format already saved space by discarding some visual information and compressing the remaining pixels very aggressively. Lossless JXL must preserve every decoded pixel exactly, so it cannot throw away more information to match the source size. It also cannot bring back detail that was lost before conversion; it preserves the image you have, not the original image before lossy compression.
PNG can also be smaller than JXL in some cases. Flat areas, such as a large solid-black background, can be extremely efficient for PNG to store. JXL may be smaller for detailed photos, gradients, and textured images, but its lossless file can be larger for simple graphics because it still has to store the exact pixels plus its own format overhead. A larger JXL does not mean the conversion reduced quality or failed.
- Lossy: smaller files, with some detail removed to achieve that size.
- Lossless: exact pixels, usually requiring more data but avoiding additional quality loss.