Dear Stepan,
the source code of FreeMASTER serial and CAN communication driver is available in the MCUXpresso SDK. The source code is the same for all MCUs supported by the SDK, so just pick any of the supported devices or boards (e.g. FRDM-K64F) and add the FreeMASTER middleware component. The sources will be located in middleware/freemaster directory in the generated SDK ZIP package.
If you ask about sources of the FreeMASTER desktop applications, then the answer is no. The sources are not publicly available.
Best regards,
Michal
