GPSD is a service daemon that monitors one or more GPSes or AIS receivers attached to a host computer through serial or USB ports, making all data on the location/course/velocity of the sensors available to be queried on TCP port 2947 of the host computer. With gpsd, multiple location-aware client applications (such as navigational and wardriving software) can share access to receivers without contention or loss of data. Also, gpsd responds to queries with a format that is substantially easier to parse than the NMEA 0183 emitted by most GPSes. The GPSD distribution includes a linkable C service library, a C++ wrapper class, and a Python module that developers of gpsd-aware applications can use to encapsulate all communication with GPSD.

Besides GPSD itself, the project provides auxiliary tools for diagnostic monitoring and profiling of receivers and feeding location-aware applications GPS/AIS logs for diagnostic purposes.