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OMX: The Open Matrix data file format

An OMX matrix file is a structured collection of two-dimensional array objects and associated metadata. OMX is built on top of the well-established HDF5 scientific data storage standard. An OMX file has a specific layout that is intended to ensure that complete and consistent information about the matrix data is stored and that the data can be retrieved correctly and efficiently. We hope for the modeling industry to adopt the OMX standard, and we will periodically review the specification to make revisions as necessary.


OMX APIs for your language

Each API is now developed in its own repository, to keep history cleaner and more focused:

More Information

Check out the OMX wiki for more information, including API user guides, how to import and export OMX matrices from EMME, VISUM, TransCAD, and Cube, where to get the OMX validator, OMX viewer, and other background information on how OMX was created.

Our previous site and listserv are no longer maintained.


All code written in the OMX project, including all API implementations, is licensed under the Apache License, version 2.0. All code (c) by its respective authors. See LICENSE.TXT for the full Apache 2.0 license text.