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. But you can make a donation to support further development of 7-Zip.
The main features of 7-Zip

* High compression ratio in new 7z format with LZMA compression
* Supported formats:
o Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
o 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

Repairing and fixing tool for corrupt or damaged ZIP archive files
Object FIX ZIP is a very useful utility that gives you the possibility to repair ZIP archive files, reconstruct the specified Zip file and try to make a new Zip archive recovering files from Zip file where possible.

Software designed for repairing and fixing of corrupt or damaged ZIP archive files which are not completely downloaded or partially damaged.

Here are some key features of “Object FIX ZIP”:

· Repairs corrupt or partially damaged ZIP archives.
· Extracts files from ZIP archives with CRC errors.
· Extracts files from partially downloaded ZIP archives.
· Extracts multiple ZIP archives with a single operation.
· Supports all ZIP archive files created with any PkZIP and WinZIP compatible archiver software, except for those using strong encryption.
· Easy-to-use, intuitive wizard-driven interface.