7-Zip

7-Zip is a file archiver with a high compression ratio. With these tools you can easily send large quantities of information or open compressed files you receive without hassle. 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.