The library is based on the work of Gerald Evenden at the United States Geological Survey (USGS),[2] but since 2019-11-26 is an Open Source Geospatial Foundation (OSGeo) project maintained by the PROJ Project Steering Committee (PSC).

The library also ships with executables for performing these transformations from the command line.

[4] It was based on the General Cartographic Transformation Package or GCTP, which consisted of Fortran subroutines that could be used to project geographic data.

[5] The third release of PROJ from 1990, was expanded to support approximately 70 cartographic projections.

After over four years of inactivity, Frank Warmerdam became the new maintainer and released version 4.4 on March 21, 2000.