Download .prj files, explore WKT definitions, and visualize map projections — all in one place. Built for cartographers, GIS analysts, and spatial data scientists.
PRJ is an open clearinghouse for spatial coordinate reference system (CRS) definitions. Every entry provides multiple machine-readable and human-readable formats: OGC WKT, WKT-2, ESRI WKT, PROJ strings, .prj files, and JSON — alongside scholarly context, mathematical descriptions, and interactive D3.js previews.
The project is hosted on GitHub Pages and contributions are welcome. If you have a projection definition to add, open a pull request.