7-Zip, Free Open Source Software

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. 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.
I love this software, the compression ratio results are very dependent upon the data used for the tests. Usually, 7-Zip compresses to 7z format 30-70% better than to zip format. And 7-Zip compresses to zip format 2-10% better than most of other zip compatible programs.
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