7-Zip is open source software which is totally free to use. You can use, download 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip. Absolutely free software with most powerful features

The main features of 7-Zip

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  High compression ratio in new 7z format with LZMA compression

  
  
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  Supported formats:

  
  
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    Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR

    
    
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    Unpacking only: ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR and Z.

    
    
  
  
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  For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 % better than the ratio provided by PKZip and WinZip

  
  
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  Self-extracting capability for 7z format

  
  
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  Strong AES-256 encryption in 7z and ZIP formats

  
  
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  Integration with Windows Shell

  
  
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  Powerful File Manager

  
  
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  Powerful command line version

  
  
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  Plug-in for FAR Manager

  
  
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  Localizations for 74 languages it’s amazing.

  
  

Download 7-Zip 4.65 (2009-02-03) for Windows:

Download 7-Zip 9.12 beta (2010-03-24) for Windows:

The download links above redirect you to download pages provided by 7-zip Organization

Source:  7-zip.org?