7zip & powerzip

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.

For more details http://www.7-zip.org/

Power zip

"PowerZip is one of my best investments and next to Windows XP my most valuable program. I use it constantly and depend upon it so much. I purchased it many years ago and am in the second update. I have a difficult time keeping track of the Product Key. Thanks for sending it so quickly. You are the best!!" More details Visit http://www.powerzip.biz/Default.aspx