chrony is a client and server for the Network Time Protocol (NTP). This program keeps your computer's clock accurate. It was specially designed to support systems with intermittent Internet connections, but it also works well in permanently connected environments. It can also use hardware reference clocks, the system real-time clock, or manual input as time references.
libmsntp is a full-featured, compact, portable SNTP library. libmsntp provides SNTP client and server functionality in a shared library with a simple API. SNTP (RFC 2030) is a simplified version of NTP, which allows precise synchronization of system clocks over a best-effort network.