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Online alarm clock

 

Type a time and press Set alarm.

    Your time zone: detected in your browser. The alarm rings while this tab is open.

    How the alarm clock works

    Set it the way you say it

    The time box takes 6:30 am, 6.30pm, 630pm, 18:30 or 1830; a bare number such as 6 means 6:00 AM on a 24-hour reading. For a delay, type in 20 min or in 1h30m. Before you set it, the line under the box says whether it will ring today or tomorrow and exactly how long that is from now, so a 6 AM / 6 PM slip is easy to catch.

    Several alarms, once or repeating

    Each alarm can ring once, every day, or Monday to Friday, with its own label. They are listed under the clock with the time left to each; switch one off without deleting it, or delete it. The next alarm and the time left are also in the tab title, so you can check it from another tab.

    Ringing, snooze and sounds

    When an alarm rings, the display flashes, the sound repeats (for up to ten minutes) and, if you allowed notifications, a system notification appears. Stop it with the button, the space bar or Esc; snooze it for 5 or 10 minutes. The five sounds are generated by your browser, so the page works without a connection once loaded; Soft rise starts quietly and gets louder.

    On time, even in a background tab

    Browsers slow down the scripts of background tabs, which makes many web alarms ring late. This one books the ring of the next alarm on the browser’s audio clock, which keeps exact time in the background, and it measures time with the clock corrected against our server, not the device clock.

    Alarms and daylight saving time

    An alarm is set for a time on the clock, not for a length of time, so a clock change affects it differently from a timer. On the night clocks spring forward, one hour of clock time never happens; on the night they fall back, one hour happens twice. This alarm clock follows the rule of the iCalendar standard that calendar software uses (RFC 5545, section 3.3.5): a skipped time is read with the offset in force before the jump, so a 2:30 AM alarm rings at 3:30 AM new time, and a repeated time rings the first time it comes around.

    Which alarm times can be affected depends on when your zone changes its clocks. These are all the local times at which any zone in the IANA database changes between 2026 and 2030:

    Local time of the changeZonesFor example
    1:00 AM9Havana, Troll, Azores, Canary, …
    2:00 AM90Casablanca, Ceuta, El Aaiun, Adak, …
    2:45 AM1Chatham
    3:00 AM38Casablanca, Ceuta, El Aaiun, Macquarie, …
    3:45 AM1Chatham
    4:00 AM11Famagusta, Nicosia, Athens, Bucharest, …
    10:00 PM1Easter
    11:00 PM2Nuuk, Scoresbysund
    Midnight (end of the day)7Cairo, Havana, Nuuk, Santiago, …

    So alarms from 5:00 AM to 8:59 PM are never skipped or repeated anywhere. Night alarms can be: between midnight and 4:59 AM in the zones that change then, and from 9:00 PM to midnight in the zones that change late in the evening (Easter Island and Greenland) or at midnight (such as Cairo and Havana). The hour that changes depends on the direction: when clocks spring forward at 2:00, the times from 2:00 to 2:59 are skipped; when they fall back at 2:00, the times from 1:00 to 1:59 happen twice.

    What an online alarm cannot do

    A web page can only ring while it is running. Phone browsers pause pages as soon as the screen locks or another app comes to the front, and a sleeping computer runs nothing, so this alarm is for a computer or tablet that stays awake with the tab open, such as a reminder during the working day or a nap at your desk. For waking up with a phone on the nightstand, the phone’s own clock app is the reliable choice.

    Browsers also refuse to play sound before you interact with a page. Pressing Set alarm counts, and it is why a shared alarm link opens ready to set instead of setting itself. If the page was paused when the alarm was due, it rings as soon as it runs again within ten minutes; an alarm missed by more than that is skipped, so it does not go off hours late.

    Keyboard shortcuts

    Enter
    Set the alarm from the time box
    Esc or Space
    Stop a ringing alarm
    S
    Snooze 5 minutes
    Tab
    Move between the controls

    Ready-made alarms

    Questions

    How do I set an online alarm?
    Type the time (for example 6:30 am, 18:30 or 630pm) and press Enter or Set alarm. The big display shows the next alarm and how long until it rings. Keep the tab open: the alarm lives in this page.
    Can I set an alarm for 5 minutes from now?
    Yes: type in 5 min (or in 1h30m) and press Enter. The alarm is set for the clock time that is that far ahead; for a pure countdown, the timer does the same thing without a clock time.
    What time is my alarm set for?
    The big display always shows the next alarm, with the day and the time left. All your alarms are listed under it, where you can switch each one off or delete it.
    Will the alarm ring if my computer or phone is asleep?
    No web page can run while the device sleeps, and phone browsers pause pages when the screen locks. Keep the device awake and the tab open. If the page was paused, it rings as soon as it wakes, as long as the alarm time is less than ten minutes past; an older missed alarm is skipped, not rung hours late.
    Does the alarm handle daylight saving time?
    Yes. It rings when your clock shows the alarm time. If a clock change skips that time (a 2:30 AM alarm on the night clocks spring forward from 2:00 to 3:00), it rings at 3:30 AM new time, as if the clocks had not moved; if the time happens twice (clocks going back), it rings the first time.
    How do I snooze or stop the alarm?
    Press Stop, the space bar or Esc to stop it, and Snooze or S to hear it again in 5 minutes (10 minutes with the other button). A repeating alarm stays set for its next day.
    Is my alarm stored anywhere?
    Only in your browser’s local storage, so it is still there after a reload. The alarm is never sent to a server, and there is no account.

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