zlib, Programming, zlib data compression library for OpenVMS From Wikipedia: zlib is an open-source, cross-platform data compression library by Jean-loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. The first public version, 0.9, was released on May 1, 1995 and was originally intended for use with libpng image library. zlib is distributed under the zlib license. For further information: