The Tokenblauser GPSDO is a laboratory-grade GPS-disciplined clock source with very low noise output, suitable for QO-100 and SHF applications, including operating FT8 and other narrow-band digital modes. Unlike many other GPSDOs with fixed 10 MHz output, it additionally generates up to four arbitrary frequencies simultaneously. This functionality is provided “out of the box”. The Tokenblauser GPSDO is also a versatile platform for experiments. The device is Arduino-compatible, and the firmware is open-source.