Set a wake-up time or a quick reminder right in your browser. Choose the time, add an optional label, and the clock rings with a tone generated locally — no app to install, no account, and no audio file to download. It is handy for power naps, timeboxing work, reminding yourself to leave, or a quiet kitchen timer when your phone is across the room.
How it works
You pick a target time of day. The page compares it to your device clock and schedules the alarm for the next time that clock reads your chosen hour and minute — today if it is still ahead, otherwise tomorrow. When the moment arrives, the alarm tone is synthesised on the spot with the browser’s Web Audio API (an oscillator), so there is no sound file to fetch and the alarm works even offline. You can then dismiss it. Because all of this happens inside the open tab, the tab must stay open and the device must stay awake.
The Web Audio API tone
The alarm tone is generated by a JavaScript oscillator node — a pure sine or square wave produced by the browser’s audio engine without downloading any file. The frequency, duration, and shape of the tone are defined in code, so the alarm works in airplane mode or on a slow connection equally well. The sound plays through whatever audio output your device is currently using (speakers or headphones), at your system volume.
Practical scenarios
Power nap timer: Set the alarm for 20–25 minutes from now and lie down. The label “Nap” reminds you what it is for when it wakes you. Because the tone is synthesised locally, it works without any network access.
Timeboxed work session: Set to ring in 45 minutes, label it “End focus block.” You can switch to other tabs or applications — the alarm continues counting in the page as long as the tab is open.
Kitchen reminder on a laptop: If your phone is away from the kitchen and your laptop is on the counter, a browser alarm can serve as a simple cooking timer. Be aware the device must stay awake; if the lid closes or sleep activates, the alarm may not fire.
Stand-up meeting nudge: Label it “Stand-up call” and set it a few minutes before the meeting. No calendar integration or account needed.
Example
It is 2:40 pm and you want a 20-minute reminder. Set the time to 3:00 pm, add the label “Stand-up call”, and press Set alarm. The page calculates that 3:00 pm is 20 minutes away and schedules the tone for then. At 3:00 pm the alarm sounds and shows your label, and you dismiss it.
If instead you set 8:30 am at 2:40 pm, the alarm rings at 8:30 the next morning, because that time has already passed for today.
Important limitations
- Tab must stay open. Unlike a phone alarm app, there is no background process. If you close or refresh the tab, the alarm is cancelled.
- Device must stay awake. Sleep, hibernate, or a locked screen will prevent the alarm from firing on most systems. Disable sleep before a nap or overnight.
- Browser audio must be permitted. Some browsers require a prior user gesture before audio can play. If the tone does not sound, check your browser’s site audio permissions and try clicking the page once first.
- Single time of day only. This fires at the next occurrence of the chosen time — no multi-alarm or specific-date scheduling. For a future date, use a countdown-to-date tool instead.
Keep the tab open and the device awake; everything runs in the page, so nothing about your alarm ever leaves your device.