Peter Mattis is a computer programmer most notable for his early work on the GNU Image Manipulation Program (GIMP).

In 1995, while students at the University of California at Berkeley

University of California, Berkeley

The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...

, Mattis and his classmate Spencer Kimball

Spencer Kimball

Spencer Kimball is a computer programmer most notable for his early work on the GNU Image Manipulation Program .In 1995, while students at the University of California at Berkeley, Kimball and his classmate Peter Mattis developed the first version of The GIMP as a class project...

 developed the first version of The GIMP as a class project. The two were also members of a student club at Berkeley called the eXperimental Computer Facility (XCF).

According to Mattis in 1999:

On free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 and the motivations to write it and what makes good and enduring free software:

Mattis works for Google. He has worked on Google Servlet Engine along with Spencer Kimball

Spencer Kimball

Spencer Kimball is a computer programmer most notable for his early work on the GNU Image Manipulation Program .In 1995, while students at the University of California at Berkeley, Kimball and his classmate Peter Mattis developed the first version of The GIMP as a class project...

.