gizmobench

Online Alarm Clock

Type a time, press Arm, and this tab rings. What is different is on the face rather than in the small print: one chip says whether an alarm is armed and for when, one says whether this browser has let the sound through yet, and one says the tab has to stay open. Those are the two ways every browser alarm quietly fails, so they are shown live on the clock face instead of being left to be discovered at the moment the alarm was supposed to help. The alarm itself is a wall clock moment rather than a counter losing a second every second, so a tab the browser has throttled in the background still rings, and the page says how late it woke up if it was late. The field takes 07:30, 7:30, 07:30:15 or 7:30 pm, a time that has already gone today is set for tomorrow, and there are three sounds, a daily repeat and a five or nine minute snooze. Nothing is uploaded, there is no account, and the alarm sound is built by the page rather than downloaded.

Now, on your device clock--:--:--Enter a time and press Arm.
Not armedThis tab must stay open
Sound
Repeat
Snooze

Not armed. Enter a time and press Arm.

  • Armed, sound unlockedthe ordinary case
    not armed yet: enter a time and press Arm
  • Sound never unlockedthe page has not been clicked
    a warning chip on the face, not a silent failure
  • Tab in the backgroundthrottled by the browser
    still rings: the alarm is a wall clock time, not a countdown of ticks

The face is a 24-hour clock, and the field takes 07:30, 7:30, 07:30:15 or 7:30 pm. A time that has already gone today is set for tomorrow. Arm opens the sound, so the alarm can play later without another click, and the tab title carries the countdown while you are looking at something else.

A desk alarm, and it says so. Accurate to the second against your device clock while this tab is open and sound is allowed. It cannot ring if the tab is closed, the device is asleep or the browser has muted the page, so it is a desk alarm and not a replacement for the alarm on your phone.

Common questions

Will the alarm go off if the tab is in the background?
Yes, as long as the tab is still open. Browsers stop drawing a hidden tab and slow its timers down, often to about one a second and eventually to one a minute, which is why an alarm that counts ticks quietly loses time and rings late or not at all. This one keeps the alarm as a moment on your device clock and every wake asks one question, whether that moment has passed, so a gap of forty minutes with no timers delivered gives exactly the same answer as forty minutes of ticking. What throttling can still cost you is a little lateness, because the tab has to wake before it can look: if it woke late, the clock face says so and tells you how late, rather than pretending it rang on time.
Does it still ring if I close the browser or shut the laptop?
No, and no browser alarm can. The page only exists while the tab does, so closing the tab, quitting the browser or shutting the machine down ends it, and a device that goes to sleep will not ring until it wakes. That is why the third chip on the face reads that this tab must stay open. If you need an alarm that survives a closed lid, use the alarm on your phone or your operating system's own clock app. This one is a desk alarm: leave the tab open on a second screen and it is the right tool, use it as your morning alarm and it is not.
Why do I have to click the page before it can play a sound?
Every modern browser refuses to let a page make noise until someone has interacted with it, which stopped autoplaying video ads and also stops a silent alarm clock. Until that click has happened, the page shows an amber chip reading that a click is needed, rather than looking armed and then failing quietly. Pressing Arm is that click, so arming an alarm also unlocks the sound. You can check it any time by clicking the sound chip on the face, which plays the alarm once at the volume it will use.
Does the alarm work offline?
Once the page has loaded, yes, it goes on working offline. Everything runs in your browser: the time you type is read there, the countdown is arithmetic on your own device clock, and the alarm is a short run of tones the page synthesises with Web Audio rather than a sound file it downloads, so no request goes out when it rings. What still needs a connection is loading or reloading the page in the first place, unless your browser already has it cached.
How do I set the time, and what do repeat and snooze do?
The alarm field takes 07:30, 7:30, 07:30:15 or a 12-hour time such as 7:30 pm, and the face itself is a 24-hour clock. A time that has already gone today is set for tomorrow, so 06:30 typed at seven in the morning is tomorrow's alarm rather than one that has already passed. Repeat set to Every day arms the alarm again for the same wall clock time the next day the moment it rings, which keeps 07:00 at 07:00 even across a daylight saving change. Snooze offers five minutes, nine minutes, the interval bedside clocks have used since the mechanical ones, or Off, and the Snooze button appears only while the alarm is actually ringing, and not at all when snooze is set to Off. Your time, sound, repeat and snooze settings are kept in this browser only, and the Start over button at the top of the page forgets them.

Accurate to the second against your device clock while this tab is open and sound is allowed. It cannot ring if the tab is closed, the device is asleep or the browser has muted the page, so it is a desk alarm and not a replacement for the alarm on your phone.