Version 33 (modified by mdavis, 12 years ago) ( diff )


Welcome to Proj4J

Proj4J is a Java library to transform point coordinates from one geographic coordinate system to another, including datum transformations.

The core of this library is a port of the PROJ.4 C library. The projection algorithms, concepts and coordinate system definitions are all taken directly from PROJ.4. These are wrapped in a Java class model which follows standard Java conventions and OO best practices.

Proj4J is a part of the MetaCRS group of projects, hosted by OSGeo.


  • Uses the PROJ.4 coordinate system definition files
  • Supports many PROJ.4 parameters
  • Implements over 90 projections
  • Provides coordinate system definitions for EPSG and ESRI authorities
  • Simple, efficient API
  • Provides a test framework compatible with the MetaCRS Test Suite
  • Provides unit tests defined in MetaCRS format


Status: Currently this library is still being created, and is not yet ready for download


  • The PROJ.4 documentation is the best reference for details of the coordinate system specification language, projection algorithms and supported parameters.
  • the Version History lists the evolution of features of the library

Mailing List

A mailing list is available for users and developers of Proj4J.


Bug Tracking


Proj4J is licensed under the Apache License, Version 2.0.

Related Resources


The Proj4J codebase is based on a partial port of PROJ.4 carried out by JHLabs circa 2006. The JHLabs port provided a large number of the PROJ.4 projections, but did not support some PROJ.4 features such as datum transformation.

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