For most of us we unknowingly decompress archives all the time. That’s because Apple built it into the Mac OSX operating system and all it takes is a double click (or sometimes automatically). However sometimes you run into a situation where that file you downloaded just won’t decompress. Hopefully this how-to will help.
Simply Decompress
Lets say you have a situation like this. You found an archive on your system which ends in a .zip, well simply enough double click on it. That’s it!
With the built in Archive Utility you can decompress .zip, .tar, and .gz files.
Pesky Compressed Files
In the world of compression there are many different flavors and many more to come. Some of the most popular of these are Zip, RAR, 7z, Tar, Gzip, Bzip2. Well as you may tell the built in Archive Utility does not cut it. This is where a beautiful open source app called The Unarchiver comes in handy. It can handle those and so much more.
First thing first you need to go and get it installed (free) via direct download or Mac App Store.
Once you have it installed you need to get it configured. My recommendation is to select all the archive formats which you want it to use, I’d recommend selecting all formats because at this point Archive Utility is pretty much obsolete. There are other options which you can explore if you so desire.
Since you now have The Unarchiver installed and configured all you need to do is double click on the archive… voila!
The Unarchiver Compression Support
Supported popular formats
| Format | Support level | Notes |
| Zip | Full | Full support for the normal zip format, with additional support for AES encryption, Zip64 extensions for large files, Mac OS extensions of many different kinds, and several unusual compression methods (Deflate64, Bzip, LZMA, PPMd). Can also extract .EXE self-extracting files using Zip. |
| RAR | Full | Including encryption and multiple volumes. Can also extract .EXE self-extracting files using RAR. |
| 7z | No encryption | Most compression methods are supported, but no encryption. Also supports Unix extensions. |
| Tar | Full | |
| Gzip | Full | |
| Bzip2 | Full | |
| LZMA, XZ | Full | Both the old “LZMA-alone” format, usually named .lzma, and the new .xz format. |
| CAB | Full | |
| MSI | Full | This format is also used by many other Microsoft formats, meanings that you can use The Unarchiver to extract internal data from DOC and PPT files, and others. There is probably no reason to do this, but you can. |
| NSIS | Extensive | Supports many different versions, starting from version 1.1o |
| EXE | Some | Many kinds of .exe self-extracting formats are supported. However, if you find one that is not, please post an issue on the bug tracker. |
| ISO, BIN | Extensive | Most common disc images can be unpacked, both normal and raw. |
| Split files | Basic | Can join files named .001, .002 that do not use any extra wrapper format. |
Supported old formats
| Format | Support level | Notes |
| StuffIt | No encryption | Can unpack all files I’ve been able to locate. |
| StuffIt X | Partial | Can unpack many files, some more obscure features are still unsupported. JPEG compression is also unsupported. |
| DiskDoubler | Almost full | Only lacks some old compression methods, because I have not been able to locate any files using these. If you have some that do not work, please post them here. |
| Compact Pro | No encryption | |
| PackIt | Full | |
| Cpio | Full | |
| Compress (.Z) | Full | |
| ARJ | No multi-part | |
| ARC, PAK | Full | Full support for all algorithms, including proprietary ones from PAK. Encryption only works in command-line utilities. |
| Ace | Only old files | No support for Ace 2.0 and up (WinAce). |
| Zoo | Full | |
| LZH | Full | |
| ADF | FFS | Can extract files from Amiga disk images using the regular FFS file system. |
| DMS | FFS | Can extract files from compressed Amiga disk images using the regular FFS file system. |
| LZX | Full | |
| PowerPacker | Full | |
| LBR | Full | |
| Squeeze | Full | |
| Crunch | Full | |
| Many other old formats, especially Amiga-specific ones, are also supported through libxad, but I have not made a full survey of which ones. | ||
Supported unusual formats
| Format | Support level | Notes |
| XAR | Full | Suggested replacement for Tar on Unix. Used in some newer .pkg files on Mac OS X. |
| RPM | Full | Linux package format. |
| ALZip | No encryption | Archive format which is mainly popular in South Korea. Support for all known compression methods, including Bzip2, Deflate and obfuscated Deflate. |
| NSA, SAR | Partial | Game data file. Can unpack all files I’ve found. If you have ones that do not unpack, please post an issue. |
| NDS | Full | Nintendo DS ROM image, which can contain a file system. |
