The World Clock takes the current moment from your own device’s clock and converts it into each selected city’s local time using your browser’s built-in Intl date library and the IANA time-zone database it ships with. Because the browser knows each zone’s daylight-saving rules, the offsets shift on the correct dates with no plugin to update. Nothing is sent to a server — the only requirement is that your device clock itself is set correctly.

Add every participant’s city to the World Clock, then use the meeting planner below. It draws a 24-hour strip for each city aligned to the same instant and colours it: green for working hours (9 a.m. to 5 p.m.), amber for early morning or evening, and grey for the middle of the night. Drag the slider to test a candidate time and the highlighted column shows that exact hour in every city, so a slot where most rows are green is your best meeting time.

Yes. Every offset is resolved live from the IANA time-zone database inside your browser rather than from a fixed table, so daylight-saving transitions are handled automatically for each city. When a region springs forward or falls back, the displayed time and the UTC offset change on the correct date without any action from you and without an update to the tool.

The World Clock is completely free with no account or limits. All time conversion happens in your browser using built-in date APIs, so nothing about your location or chosen cities is sent to any server. Your selected cities and your 12 or 24-hour preference are stored only in your browser’s local storage, and the tool keeps working offline after the first load.