The Unarchiver is a much more capable replacement for "Archive Utility.app", the built-in archive extraction program on Mac OS X. The Unarchiver is designed to handle many more formats than Archive Utility, and to better fit in with the design of the Finder. It can also handle filenames in foreign character sets, created with non-English versions of other operating systems. I personally find it useful for opening Japanese archives, but it should handle many other languages just as well.
It is very simple to use and install - simply copy it into your Applications folder, or whereever else you might prefer, and then set it as the default program for archive files. This can be done either from the preferences panel in the program itself, or in the Finder.
Supported file formats include Zip, Tar-GZip, Tar-BZip2, RAR, 7-zip, LhA, StuffIt and many other old and obscure formats. See the supported formats page for a more complete list of supported formats.Download it now from the Mac App Store!
The Unarchiver is completely free, and will always remain free. If you appreciate the hard work that has gone into writing it, you can use the buttons below to donate and support the developer.
You can also buy The Archive Browser for OS X and Archives for iOS to support development of The Unarchiver!
If you do not wish to use the Mac App Store, you can download The Unarchiver directly. There are two versions: The Mac App Store version and a version for older Mac OS X versions. The latter is not sandboxed, and might work better if you experience strange problems, or if oyu are annoyed by the nagging the program is forced to do to get around sandboxing limitations.
The source code is also available, both as an archive and on the Google Code page.
If for some reason you want an old version of The Unarchiver, you can find those either here or here.
If you have any trouble with The Unarchiver, please file a bug on the bug tracker, or post a question on the support board.