Build the set once
Add the zones you actually work with, give each one a label — a person, an office, a client — and the set is saved in your browser. It will be there next time without setting it up again. Add as many as you need; the layout stays readable.
Share it as a link
The Copy Link button encodes your whole set of zones into a URL. Send it to a colleague and they see the same board you do, without installing anything or creating an account. This is the fastest way to settle a scheduling argument across three continents.
Offsets are not fixed
The gap between two cities changes through the year, because countries start and end daylight saving on different dates — and some do not observe it at all. London and New York are five hours apart for most of the year but four hours apart for two short windows each spring and autumn. This clock reads live timezone data, so the offsets shown are correct for today rather than for an average.