ClockA big clock with a full screen view, alarms that ring in this tab, a countdown timer, a stopwatch with lap times and a world clock for any city, with nothing uploaded.
No alarms yet.
No alarms yet. Press New alarm to add one.
Alarms ring only while this page is open in a tab and the device is awake. A tab behind other tabs can ring a little late; a closed tab, a closed laptop or a phone that has put the browser to sleep cannot ring. For an alarm you must not miss, set one on your phone as well.
Compare any city with your own time.
Keys while you use the tool: 1 to 5 switch tabs, Space starts and pauses, L lap, R reset, F full screen clock.
The Clock tab shows the time with seconds, the date and your time zone beside an analogue clock. Choose 12 or 24 hours, turn the seconds off, pick one of six clock faces, or press Full screen for a big clock you can read across the room.
On the Alarms tab press New alarm, pick the time, add a label such as Wake up or Call home, and choose the days it repeats or leave it as a one-off. Pick one of five sounds and listen to it before you save.
Leave the page open in a tab and click it once after it opens, so the browser lets it make sound. When an alarm rings, a window with Snooze 5 min and Dismiss covers the page; turn on notifications to see it from other tabs.
On the Timer tab set hours, minutes and seconds, or tap a preset from 1 minute to 1 hour. The ring empties as the time runs out, the line under it says when it ends, and +1:00 adds a minute while it runs.
On the Stopwatch tab press Start, then Lap at the end of each lap or round. Every lap shows its own time and the running total, with the fastest and slowest lap marked. Space starts and stops, L adds a lap and R resets.
On the World tab type a city or a time zone, or tap one of the popular cities. Each card shows the time there, the date, the difference from your time and whether it is already tomorrow or still yesterday.
A clock, alarms, a timer, a stopwatch and a world clock share one page, so a running timer, a stopwatch and tomorrow's alarm all stay in the same tab, with a dot on each tab that is running.
Alarms ring by comparing with the clock, so a tab woken late still rings, and an alarm that could not ring because the page was closed is marked as missed instead of being skipped without a word.
The time in every city follows the time zone rules built into your browser, and an alarm set in the hour the clocks skip or repeat still rings once, at a time the page tells you in advance.
Full screen turns the screen into a large clock with the date, in the light or dark theme of the site, for a desk, a classroom, a stage or a kitchen. F opens it and closes it again.
The keys 1 to 5 switch tabs, Space starts and pauses the timer and the stopwatch, L adds a lap, R resets and F opens the full screen clock, whenever the tool is in use and you are not typing.
Every alarm sound is made in your browser, and your alarms, cities and settings stay on your device, kept in this browser between visits. A backup file moves them to another browser.
Browsers and phones share one public list of the world's time zones and their summer time rules, the tz database. A city's time here comes from it, and a few zones it has renamed, such as Kolkata (once Calcutta) or Kyiv (once Kiev), are shown under their current names.
To save power, browsers wake a tab that is out of sight far less often than one you are looking at. The page sets an extra timer for the next alarm when you switch away and compares with the clock at every check, but a closed tab or a sleeping device cannot run at all.
Where clocks go forward in spring, one hour of the night never happens; where they go back in autumn, one hour happens twice. An alarm inside the skipped hour rings as many minutes later as the clocks jumped, and one inside the repeated hour rings the first time.
It is free, with no registration. Like every page on ZeroDataUpload, it is supported by advertising. Every alarm sound is made in your browser, and your alarms, cities and settings stay on your device: they are kept in this browser between visits and never sent to a server. Delete everything, under Sound and settings, removes them.
No. A web page can only ring while it is open in a tab and the device is awake. A closed tab, a laptop with its lid shut or a phone that has put the browser to sleep cannot ring. When you come back, the Alarms tab shows any alarm that was missed while the page could not ring. For an alarm you must not miss, set one on your phone as well.
Browsers keep a page silent until you have clicked, tapped or pressed a key on it since it opened. If you set an alarm and then reload the page, the alarm could only ring in silence, so the page shows a note until you click anywhere on it once. After that the sound works for as long as the tab stays open.
Yes, as long as this tab stays open. Browsers wake tabs that are out of sight less often to save power, so the page sets one extra timer for the next alarm when you switch away, and every check compares with the clock rather than counting ticks. A hidden tab can still ring a little late. Turn on notifications in Sound and settings to see a message when an alarm rings while you are in another tab or window.
Every city's time comes from the time zone rules built into your browser, the same tz database that phones and computers use, so a change to or from summer time is followed on the right date. The difference from your time and whether the city is already on tomorrow or still on yesterday are worked out for each city every second.
In places with summer time, one night a year skips an hour and another repeats one. An alarm set inside the skipped hour, such as 2:30 when the clocks jump from 2:00 to 3:00, rings at 3:30, as late as the clocks jumped. An alarm inside the repeated hour rings once, the first time that time comes round.
The Time Zone Converter converts a time you type between zones and plans meetings across them; the World clock tab here shows the time now in the cities you pick, next to your alarms and timers. The Epoch Converter counts down to a date and turns timestamps into dates; the Timer here is a kitchen-style countdown of hours, minutes and seconds that rings when it reaches zero.