The OpenSpirit C++ API is available on Windows, Linux, and Solaris in both 32 and 64 bit versions.

The OpenSpirit SDK comes with an example C++ application that uses QT  that illustrates the use of the C++ API services. 

The C++ API documentation may be found here (a 3.0 MByte .zip file - Note that you must right click the downloaded file and change it to "unblock" before it can be used...)