CellML API
The CellML API project.
The CellML API and implementation is a Free / Open Source project, giving you the choice of either building it yourself from source, or downloading pre-built binaries (for Windows, Mac, and Linux). For further information on the CellML API, please refer to the CellML API website.
See also the libCellML project for an alternative implementation of CellML support that has recently begun.