ABC is a free data compression program based on the Burrows-Wheeler transformation. The source code is free for academic, research and educational use as depicted in the Abel Public License (APL). The program is developed in DELPHI as a command line program just like GZIP.

Update: Jürgen has released the source code for ABC at long last! The Delphi source is available for download from the web site and can be used under his own APL.

http://www.data-compression.info/ABC/