ZPAQ is a System Utilities software developed by Matt Mahoney. After our trial and test, the software is proved to be official, secure and free. Here is the official description for ZPAQ:
BS Editor: ZPAQ is an open format for compressed data (like deflate), supported by an Archiver (like zip) and a Library API for developers (like zlib). Like deflate/zlib/zip, ZPAQ is free, open source, and not encumbered by patents, but it is designed for for high compression ratios rather than high speed. you can free download ZPAQ 4.03 now.