Harbour is a modern computer programming language. It is a Clipper-compatible compiler which is cross-platform, running on many operating systems (DOS, Microsoft Windows, Linux, Unix variants, several BSD descendants, Mac OS X, MINIX 3, Windows CE, Pocket PC, Symbian, iPhone, QNX, VxWorks, OS/2/eComStation, BeOS/Haiku) using the same source code and databases.
Although it is a powerful general-purpose programming language, it was primarily used to create database/business programs. Harbour have been actively maintained looking for diversity keeping backward-compatible with Clipper style. It has undergone many changes and revisions and regain widely popularity amongst programmers in 1980s and 1990s.
The open source Harbour license is similar to the GNU General Public License, with an exception supporting proprietary applications, so proprietary applications can be produced with Harbour and distributed.