Wikipedia
Info-ZIP is a set of open-source software to handle ZIP archives. It has been in circulation since 1989. It consists of 4 separately-installable packages: the Zip and UnZip command-line utilities; and WiZ and MacZip, which are graphical user interfaces for archiving programs in Microsoft Windows and classic Mac OS, respectively.
Info-ZIP's Zip and UnZip have been ported to dozens of computing platforms. The UnZip web page describes UnZip as "The Third Most Portable Program in the World", surpassed by Hello World, C-Kermit, and possibly the Linux kernel. The "zip" and "unzip" programs included with most Linux and Unix distributions are Info-ZIP's Zip and UnZip.
In addition to the Info-ZIP releases themselves, parts of Info-ZIP, including zlib, have been used in numerous other file archivers and other programs. Many Info-ZIP programmers have also been involved in other projects closely related to the DEFLATE compression algorithm, such as the PNG image format and the zlib software library.