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 7z format with LZMA and LZMA2 compression Supported formats: Packing / unpacking: 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM Unpacking only: ARJ, CAB, CHM, CPIO, CramFS, DEB, DMG, FAT, HFS, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, RAR, RPM, SquashFS, UDF, VHD, 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 79 languages Site: http://www.7-zip.org/