JBF is an extension that is specific to files used by the Paint Shop Pro graphics editor. A JBF is a file containing a set of image thumbnails available in the program's photo viewer. This solution allows the user to preview the contents of files without having to open it.

The program viewer automatically updates the JBF cache file depending on what images are viewed in the application. When a user opens a folder that contains photos, the browser creates a thumbnail file called PspBrwse.jbf.