This library adds zip compression and decompression functionality to your program, allowing you to create and modify ZIP files in a compatible way with WinZip, PKZIP and other popular archivers. Its easy and practical interface makes the library suitable for the beginners as well as for the advanced users. The library is published under the GPL - alternate licensing needs to be arranged if you wish to use this in a commercial product.

http://www.artpol-software.com/index_zip.html