An ARJ file is a compressed archive created with the ARJ or ARJ32. It saves disk space by compressing multiple files into a single archive using the Robert Jung compression algorithm.

ARJ is a flexible archiving program developed for DOS, Windows 95, 98, and Millenium Edition. ARJ32 is a 32-bit console version of ARJ designed for Windows 95 and later, including Windows 2000 and Windows XP.