XZ Utils are a complete C99 implementation of the .xz file format. XZ Utils were originally written for POSIX systems but have been ported to a few non-POSIX systems as well. The core of the XZ Utils compression code is based on LZMA SDK but it has been modified significantly to be suitable for XZ Utils. liblzma is a compression library with an API similar to that of zlib. xz is a command line too