What is IrfanView?
IrfanView is a free program for Windows that allows the user to view, edit, organize, and convert images. It is a small, fast, and easy-to-use program that can handle a wide variety of graphic formats. Furthermore, it is capable of creating and painting pictures as well as playing video and audio files. A free version of IrfanView is available for non-commercial use, whereas a registered version is available for commercial use. It was first released in 1996.
IrfanView JXL Support
A new evaluation copy of IrfanView has recently been released by the developer, which includes JXL support. A Reddit user, Jaystarx, has been in touch with the developer and provided a link to the version on the JPEG XL subreddit. Upon consultation with the developer, he made the version available for experienced JXL users to test Irfanview's compatibility to ensure that it works correctly before the official release.
IrfanView JXL Tutorial
Download the preview with the link below Unzip the content directly into the common IrfanView folder Overwrite any files in the process Make sure the JXL plugin is activated (Help>Installed plugins> JPEG_XL.DLL)
The files can then be read and saved as JXL. The basic JXL settings (Save Quality and Speed Effort) can then be adjusted, and a checkbox option is provided to save the JXL as a Progressive JXL.

Irfanview can also be associated with JXL files if you want to click on the JXL file directly from Explorer. Go to the menu: Options > Properties/Settings > Extensions, and in the list of file-types, tick the 'JXL' checkbox.
Download link
http://www.irfanview.info/test/iview64_test.zipPlease note: The JXL library is still in active development. With new APIs being added, certain features being rewritten, and possible bugs and security issues have yet to be tested.
Huge thanks to Reddit user Jaystarx, who is the primary source of this blog post!