As a superset of JPEG/JFIF encoding, it features a compression mode built on a traditional block-based transform coding core.

Other collaborators are Sami Boukortt, Alex Deymo, Moritz Firsching, Thomas Fischbacher, Eugene Kliuchnikov, Robert Obryk, Alexander Rhatushnyak, Zoltan Szabadka, Lode Vandevenne, and Jan Wassenberg.

[6] To reach widespread adoption (unlike previous attempts, including several JPEG standards), the designers hope for beneficial network effects by offering the single best option for as many popular use cases as possible.

Following a study about the most popular JPEG quality on the Web, developers paid special attention to the range with negligible or no perceived loss, and the default settings were adjusted accordingly.

The standard is expected to outperform the still image compression performance shown by HEIC, AVIF, WebP, and JPEG 2000.

In 2017 Google's data compression research team in Zurich published the PIK format, the prototype for the frequency transform coding mode.

In 2018, the Joint Photographic Experts Group (JTC1 / SC29 / WG1) published a call for proposals for JPEG XL, its next-generation image coding standard.

[5][15] Besides Cloudinary, throughout JPEG XL's preliminary implementation in web browsers, various representatives of well-known industry brand names have publicly voiced support for JPEG XL as their preferred choice, including Facebook,[16][17] Adobe,[18][19] Intel and the Video Electronics Standards Association,[20][21] The Guardian,[22][23] Flickr and SmugMug,[24] Shopify,[25] the Krita Foundation,[26] and Serif Ltd.[27] Google's stance on JPEG XL is ambiguous, as it has contributed to the format but refrained from shipping an implementation of it in its browser.

[34] Mozilla expressed security concerns, as they feel that the rather bulky reference decoder would add a substantial amount of attack surface to Firefox.

The main features are:[41][42][43] Compression: Data reduction: Versatile and future-proof size limits: Data structuring: Upgrade path: Freedom to use, batteries included: JPEG XL is based on ideas from Google's PIK format and Cloudinary's FUIF format (which was in turn based on FLIF).

[49] Modular mode allows lossy compression with the help of the modified Haar transform called "squeeze" which has progressive properties, quality of the image increases with the amount of data loaded.

[50] Prediction is run using a pixel-by-pixel decorrelator without side information, including a parameterized self-correcting weighted ensemble of predictors.

[54] In addition to the eponymous codec library, it packages a suite of auxiliary tools, like the command line encoder cjxl and decoder djxl, the fast lossless-only encoder fjxl, the image codec benchmarking tool (speed, quality) benchmark_xl, as well as the GIMP and gdk-pixbuf plugin file-jxl.