As most third-party programs do not come in source code, they need to provide a way to link other object code to it. On Windows platforms, many commercial programs in question can access DLLs from other suppliers, in which case a DLL-version of ChemApp would be used. Other programs provide a FORTRAN or C/C++ programming interface, and ChemApp can be linked to the application program.
Please contact GTT-Technologies if you are unsure whether a specific third-party program will be able access ChemApp. We will be happy to help you finding out.