World Time Zones
A speed experiment:
Simultaneous calculation of the current time, and next clock change date, in 130,000+ cities.
It uses our own custom C++ libraries on the server to do most of the timezone calculations.
Extra Credits & Copyrights:
Zoneinfo time zone database is in the public domain
Geonames location database is licensed under a Creative Commons Attribution 3.0 License
Astronomy and time algorithms - Copyright © 2011-13 Relative Data, Inc.
All Rights Reserved