Pulsar is a wireless time transfer platform that can achieve clock synchronization to better than five nanosecond between indoor or GPS-denied devices. Nanosecond-level clock synchronization is a missing capability for many real-time applications like next-generation wireless systems that leverage spatial multiplexing to improve channel capacity and provide services like time-of-flight localization. With fine- grained synchronization, both clock stability and propagation delays introduce significant sources of error. Pulsar leverages a stable clock source derived from a Chip-Scale Atomic Clock (CSAC) along with an Ultra-WideBand (UWB) radio able to perform sub-nanosecond packet time-stamping to estimate and correct for clock offsets.