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
• Supported formats:
  • 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