Ghostscript is a freely available PostScript interpreter which is available for many platforms. It is a near-essential complement to a TeX installation, used in many utilities, including PostScript/PDF viewers such as gv and GSview.

The latest version of ghostscript is (nowadays) released under the GNU General Public Licence. Older versions were first released under a nonfree licence (AFPL): some of these old versions remain on CTAN.

The author is L. Peter Deutsch.