Developer tools
Time zone converter
Stack the zones you care about and see where working hours overlap. Drag a strip to scrub to any moment. Everything runs in your browser - nothing is uploaded.
How it works
Add the cities or zones you care about and this converter stacks them as rows, each with a 24-hour strip. The strips share a single timeline, so the same horizontal position is the same instant in every row, and a working-hours band is shaded on each one. Because the bands sit at different places depending on each zone's offset, you can see at a glance where everyone's day overlaps, which makes finding a meeting time that suits everybody straightforward.
By default the panel shows the current time, ticking live, with your own zone pinned at the top. Drag along a strip to scrub to another moment and every row updates together, including the date, with a +1 or -1 badge when it is already tomorrow or still yesterday somewhere. Daylight saving is handled automatically because each offset is worked out for the exact instant shown. Your list of zones and your working hours are saved in your browser, and nothing is ever uploaded.
Example. Add New York, London, and Tokyo alongside your local zone and set working hours to 9 to 17. The shaded bands line up so you can see that mid-afternoon in London is still morning in New York and already evening in Tokyo, and the narrow stretch where all three overlap is your window for a call.
FAQ
How do the aligned strips work?
Every row uses the same left-to-right timeline measured in absolute time, so a vertical line through the panel marks one single instant across all zones. Each zone's own clock hours are labelled along its strip, and its working-hours range is shaded. Where the shaded bands of different zones line up is a time that falls within working hours for all of them.
Does it handle daylight saving time?
Yes. The offset for each zone is computed for the specific moment shown, using the browser's time zone database, so daylight-saving changes are applied correctly. If you scrub across the date when a zone switches, its strip shifts by an hour at that point, just as real clocks do.
Which time zones can I add, and are they saved?
You can add any IANA zone the browser knows, searching by city or region name. Your selected zones, their order, and your chosen working-hours window are stored in your browser's local storage, so they are still there next time. Your own zone is detected automatically and pinned at the top.
Is anything sent to a server?
No. All the time-zone maths and formatting use the browser's built-in Intl functions and run entirely on your machine. Nothing about the zones you pick or the times you view is uploaded, logged, or stored, and it works offline once loaded.