Hi @hdeboom, The existing SDK is indeed fully compatible with the Tobii C4 Eye Tracker. The SDK Tobii provide is indeed the only means by which to access the gaze data however please bear in mind that the long term storage of eye tracking data (for example to be used for scientific research) is prohibited in the SDK licence agreement. Hopefully what you had in mind does not entail this. In any event, if you could provide further details of the project you hoped to work on, we can be of further service.