How does the world clock know my local time?

The clock reads your local time directly from your device using the browser's Date API. No location permission is required, and your location is never sent to any server — the time is determined entirely from your device's system clock and timezone settings.

Does the world clock handle daylight saving time automatically?

Yes. All city clocks use the IANA timezone database (the same one used by operating systems and browsers) which automatically applies the correct daylight saving time offsets for each city throughout the year.

How many cities can I add to the world clock?

You can add as many city clocks as you need. The clocks are displayed in a responsive grid, so adding more cities simply expands the grid. Your selections are saved in browser local storage so they persist between visits.

Clock — World Clocks & Local Time