It's easy for Windows users to forget that WinZip isn't the only file-compression utility in the world. Like its better-known competitors, the free 7-Zip unpacks a host of archive formats, including ZIP, TAR, GZ, and its own 7z format. Unlike WinZip, though, it can create TAR and GZ archives, which are commonly used on Unix and Linux systems.

The program's ability to shrink files was stunning. In our tests, 7z archives were up to 40 percent smaller then their ZIP equivalents, although compression did take longer, and the highest compression settings can hog system resources. Advanced options include the ability to create solid and self-extracting archives, and to adjust the compression level and password protection. The program also has a command line module. Though the main interface is overly simple and looks like it was designed for Windows 95, it's not hard to use and fairly self-explanatory. The context menu options, which include "testing" an archive, indicate that 7-Zip should be taken seriously.

7-Zip is fine for casual users with a bit of computer savvy, but it's especially well-suited for developers and anyone else who moves between the Windows and Linux/Unix worlds.

The main features of 7-Zip:
High compression ratio in new 7z format with LZMA compression
Supported formats:
Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
Unpacking only: RAR, CAB, ISO, ARJ, LZH, CHM, MSI, WIM, Z, CPIO, RPM, DEB and NSIS
For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 % better than the ratio provided by PKZip and WinZip
Self-extracting capability for 7z format
Integration with Windows Shell
Powerful File Manager
Powerful command line version
Plugin for FAR Manager
Localizations for 69 languages