.arj

What is a .arj file?

ARJ is a legacy DOS-era archive format from the early 1990s — you'll only encounter it in very old software archives.

Safe format
Type Archive
By Robert K. Jung
MIME application/x-arj

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What is it

ARJ was one of the dominant archive formats in the DOS era, competing with PKZIP and LHA in the late 1980s and early 1990s. It offered features ahead of its time: multi-volume spanning (split archives across multiple floppy disks), archive comments, and decent compression. Bulletin board systems (BBS) distributed shareware in ARJ archives.

The format lost the compression wars to ZIP and RAR by the mid-1990s. Windows 95's built-in ZIP support was the final blow — when the operating system handles one format natively, competitors struggle to survive. ARJ's creator, Robert Jung, maintained the software into the 2000s, but new users effectively stopped adopting it.

You'll only encounter ARJ files in retro computing contexts: old BBS archives, vintage software collections, and DOS game distributions. 7-Zip extracts ARJ files. On Linux, the `arj` package handles extraction. There is genuinely no reason to create new ARJ archives.

Technical details
Full Name
ARJ Archive
MIME Type
application/x-arj
Developer
Robert K. Jung
Magic Bytes
60 EA
Safety
.arj is a known, safe format. Legacy archive format. Contents may include old software — exercise normal caution.
What opens it
7-Zip
FREE Windows
The Unarchiver
FREE Mac
arj (CLI)
FREE Linux
FAQ
How do I open an ARJ file?
7-Zip (Windows) or The Unarchiver (Mac) extract ARJ files. On Linux, install the `arj` package. Most modern archive tools support the format despite its age.
Is ARJ still used?
No. ARJ is a historical curiosity from the DOS era. You'll only encounter it in retro computing archives. Use ZIP, 7z, or tar.gz for modern archiving.
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