OSGeo/PROJ

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

2007 stars · 903 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

PROJ is a C++ library for generic coordinate transformation, converting coordinates between coordinate reference systems (CRS), including cartographic projections and geodetic transformations. It also ships command-line utilities such as proj, cs2cs, geod, cct, and projinfo for projection and transformation tasks.

Use cases

• transform coordinates between coordinate reference systems
• project geodetic coordinates to a map projection
• convert lat/lon to UTM
• perform geodesic great circle distance calculations
• look up CRS definitions and coordinate operations
• reproject GIS data to a different datum

When to choose

• you need accurate, standards-based CRS transformations in C/C++ or via bindings
• you want battle-tested geodetic datum shift and grid-based transformations
• you need CLI tools for quick one-off coordinate conversions

When to avoid

• you only need simple distance math without CRS handling
• you need a high-level GIS data format reader/writer (use GDAL/OGR instead)
• you cannot manage the proj-data grid resource files required for some datum shifts

Facets

library · maturity stable

geospatial cli developer-tools cross-platform windows cpp cli coordinate-reference-systems cartographic-projections geodetic-transformations gis crs geospatial maps linux macos

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markdown · JSON · MCP: product_card(name="OSGeo/PROJ")