ARJ (Archived by Robert Jung) is a software tool designed by Robert K. Jung for creating high-efficiency compressed file archives. ARJ is currently on version 2.86 for DOS and 3.20 for Microsoft Windows and supports 16-bit, 32-bit and 64-bit Intel architectures.
ARJ was one of two mainstream[clarification needed] archivers for DOS and Windows during the early and mid-1990s, with PKZIP being its competition. Parts of ARJ were covered by U.S. Patent 5,140,321 (expired).
File format support in other software
ARJ archives can be unpacked with various tools other than the ARJ software. There exists a free software re-implementation of the tool. A number of software utilities, including 7-Zip, Zipeg, and WinRAR can also unpack .arj files. For macOS, standalone utilities, such as DeArj and UnArjMac, are available.