ARJ

File Format
Name	ARJ
Ontology	Electronic File Formats Archiving ARJ
Extension(s)	.arj
PRONOM	fmt/610
Wikidata ID	Q2693033
Released	1990 (beta), 1991 (v1.00)

ARJ is a compressed archive format, and associated software. It was developed by Robert Jung.

ARJ was one of the leading compression tools during the 1990s. While it was a bit slower than PKZIP, it sported many more options, some of which were unique during that time (archives over multiple disks/volumes, fine-tuning of the compression algorithms used based on the data that was being compressed, recovery records to recover from simple transmission errors, etc.).

See also:

• JAR (ARJ Software)
• SDN (SDN Project)

Identification

An ARJ archive starts with signature bytes 0x60 0xea.

The full identification algorithm used by the ARJ software is given in its technical documentation.

Specifications

• The ARJ/UNARJ distributions include detailed format information, in a file named TECHNOTE.TXT or similar.
  • A copy of the 2001-09 version (with an addendum of some sort)
• The ARJ Archive File Format, from fileformat.info and Corion.net

Software

• Official homepage of ARJ software
• ARJ - Official compression/decompression software for DOS
  • v0.13a (1990-09-29)
  • v1.00 (1991-02-07)
  • v2.30 (1992-01-19)
  • v2.41a (1993-07-10)
  • v2.50a (1995-12-12)
  • v2.71 (1999-12-19)
  • v2.86 (2012-01-02)
• ARJ32 - Official compression/decompression software for Windows console
  • v3.04 (1999-12-19)
  • v3.20 (2012-01-02)
• UNARJ - Official software, decompression only
  • v2.41 (1993-04) - Source code + DOS binary
  • v2.65 (2002-06) - Source code + DOS binary + Windows console binary
• 7-Zip
• Open-source ARJ
• Konvertor

Ed. note: Some newer versions of ARJ/ARJ32 have a long delay (2 minutes?) when you run them.

Sample files

• http://cd.textfiles.com/20mnn/HPTEXT/PHRACK/
• The Silver Collection CDs have many ARJ files

Links

• Wikipedia article