7-Zip is open source software. Most of the source code is under the GNU LGPL license. The unRAR code is under a mixed license: GNU LGPL + unRAR restrictions. Check license information here: 7-Zip license.
You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip.
The main features of 7-Zip:
High compression ratio in new 7z format with LZMA compression
Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
Unpacking only: ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR and Z.
For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 % better than the ratio provided by PKZip and WinZip
Strong AES-256 encryption in 7z and ZIP formats
Self-extracting capability for 7z format
Integration with Windows Shell
Powerful File Manager
Powerful command line version
Plugin for FAR Manager
Localizations for 74 languages
7-Zip works in Windows 7 / Vista / XP / 2008 / 2003 / 2000 / NT / ME / 98. There is a port of the command line version to Linux/Unix.
Other Info: Noctua chipset cooler fitted with after market cooling also fitted to VRMs on the Motherboard.
A Version 9.20 of the free 7-Zip archival utility has been released. This major update contains a range of changes including support for LZMA2, XZ and PPMd, updating of solid .7z archives, speed optimizations, as well as bug fixes.