Timezone Converter is a timezone converter for people who work across borders. Set a time in one place, see it everywhere else, and scrub through the day to find the hours where everyone is awake.
It's free. No account, no paywall, no limits. Nothing you enter leaves your browser — your chosen cities are stored locally on your own device, so bookmarking the page brings your setup straight back.
How the math works. Conversions use your browser's built-in IANA timezone database, the same one operating systems ship with. That means daylight saving transitions, half-hour offsets, and historical rule changes are all handled correctly, with no server round trip.
Shortcuts. Press k to add a city, n to jump back to now, and c to copy every time as plain text.