Version 29 (modified by mdavis, 13 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.


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. Subscription, unsubscription and a web archive can be found at For convenience, here is a direct link to the mailing list archive.


Bug Tracking

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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