If you have your own server, why not consider joining the pool.ntp.org project to help provide accurate time to many client machines?
NTP, or Network Time Protocol, is a method for computers to obtain the current time accurately in order to keep their clocks correct. Even when set accurately, the clock on most computers will eventually drift until it is no longer accurate - often made worse when the computer is being heavily loaded.
NTP allows a client to ask a time server to tell it the current time. The “main” timeservers have accurate timekeeping equipment connected (GPS receivers are common) to give them the correct time. Other timeservers simply keep in sync with several main servers, and accept requests from client machines.