The Unarchiver

The Unarchiver is an ad-supported^[3] data decompression utility, which supports more formats than Archive Utility^[4] (formerly known as BOMArchiveHelper), the built-in archive unpacker program in macOS. It can also handle filenames in various character encodings, created using operating system versions that use those character encodings.^[5] The latest version requires Mac OS X Lion or higher. The Unarchiver does not compress files.^[6]

The Unarchiver
Original author(s)	Dag Ågren
Developer(s)	Circlesoft, MacPaw[1]
Stable release	4.3.8[2]  / 16 May 2024
Repository	heptapod.host/DagAgren/TheUnarchiver
Operating system	macOS, Linux using GNUstep libraries, and command line only on Microsoft Windows, Linux, macOS
Available in	18 languages
List of languages English, Arabic, Bulgarian, Czech, Dutch, French, German, Hungarian, Italian, Japanese, Latvian, Norwegian Bokmål, Polish, Portuguese, Russian, Simplified Chinese, Spanish, Turkish
Type	File Extractor / Decompressor
License	Proprietary since acquisition[3] Formerly LGPLv2.1-or-later
Website	theunarchiver.com

Prior to the purchase by MacPaw in 2017,^[7] The Unarchiver was free software licensed under the LGPL, up to version 3.11.1 (released 2016).^[8] This version, and the versions prior to the buyout, are still available for download from Dag Ågren’s original website.^[9] The Unarchiver version 3.11.1 provided a free-software implementation of extraction of RAR versions up to RAR5.^[10][11]

The corresponding command line utilities unar and lsar are free software licensed under the LGPL^[12][13] run on Microsoft Windows, Linux, and macOS.^[14]

A key feature of The Unarchiver is its ability to handle many old or obscure archive formats, including StuffIt, AmigaOS disk images, and LZH/LZX archives. The source code credits libxad, an Amiga file format library. Ågren also reverse engineered the StuffIt and StuffIt X formats. His work resulted in one of the most complete open source implementations of these proprietary formats.