BrowserTools

World Clock

Compare time across world cities

By Guga — BrowserTools maintainer, Tbilisi, Georgia Updated 2026-09-16
Free Private No uploads
What is World Clock?

Eight cities are loaded by default and the display refreshes every second. Each one shows its local time, the date, and its current UTC offset, so you can see not just that it is fourteen hours ahead but whether that offset is GMT+1 or GMT+2 today. A sun or moon marker tells you roughly whether it is business hours there — the marker appears between 8pm and 6am local time, which is a crude but useful signal when you are trying to work out whether to send a message now. Your own zone is shown at the top. Adding a city means typing into the search box, which matches against the browser's full list of IANA time zone identifiers and returns up to eight matches, so both 'Paris' and 'Europe/Paris' find it. Formatting goes through the browser's own locale data, so the offsets and daylight saving rules are current.

Check the current time in cities across every timezone at a glance, and add your own. Great for scheduling meetings across time zones without doing offset math in your head.

Private World Clock In Your Browser

World Clock is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.

Step-by-Step

How to use World Clock

1

Read your own local time and zone at the top of the panel.

2

Check the default cities below, each showing time, date, UTC offset and a day or night marker.

3

Type a city or zone into the search box to filter the browser's list of time zones.

4

Click a result to add it, and use the ✕ on any card to take a city off the clock.

Key Capabilities
  • Every card shows the UTC offset in effect right now rather than a fixed summer or winter value, so daylight saving changes are reflected automatically.
  • Time and date formatting runs through Intl.DateTimeFormat against the IANA database bundled with the browser, not a hard-coded table of offsets.
  • The add-a-city search covers the browser's full list of time zone identifiers and returns up to eight matches at a time.
  • A day or night marker based on the local hour gives a quick read on whether a city is reachable without opening a second source.
Common Use Cases
  • A remote team lead checks whether three colleagues are awake before sending an overnight message.
  • A caller scheduling a call with an overseas client reads the offset on each card to find an overlap.
  • A developer debugging a log timestamps compares a server's UTC time against local times in two regions.
Clear Answers

Frequently Asked Questions

How often does it refresh?
Once a second. That is a display refresh — the underlying clock is your system clock, read afresh each tick rather than advanced by counting.
Why does a city sometimes show the wrong day or date?
It should not — each card is formatted for its own zone, so a city in the next time zone can legitimately show tomorrow's date while you are still on the previous one. That is the point of the panel.
Can I search by city name?
Yes. The search matches against IANA identifiers, which almost always contain the city name. 'Chicago' finds America/Chicago; 'Chicago' alone is not a valid identifier in every implementation, so the full region-qualified form is safest.
Where does the time zone data come from?
Your browser's copy of the IANA time zone database. It is updated with the browser, which is why the offsets reflect the current daylight saving rules rather than a fixed snapshot.