It gets louder until you move
Six synthesised tones including an air horn, with an option to fade the volume up gradually instead. Nothing is a quiet three-second chirp that stops on its own.
Your local time, live
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Online alarm clock
Keep this tab open and your volume up. Press Enter to start, Esc to cancel.
Time to get up
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Answer correctly to switch the alarm off. Get it wrong and you get a new one.
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Built for people who sleep through alarms
Most browser alarm clocks make one polite noise and give up. This one is designed around the single hardest problem in waking up: you are not conscious when the decision to switch it off gets made.
You have to solve something to turn it off
Switch on the maths challenge and the alarm will not stop for a sleepy swipe. It is the one mechanic that reliably separates waking up from dreaming you woke up.
Your screen stays awake
We hold a screen wake lock while an alarm is armed, so the display does not dim and suspend the tab before morning.
The rest of the toolkit
Everything here runs in the browser, needs no account, and works on a phone as well as a laptop.
Countdown timer
Count down from any duration. Presets for 5, 10, 20 and 45 minutes.
Stopwatch
Count up with lap splits, accurate to a hundredth of a second.
Bedtime calculator
Work backwards from your wake time so you land between sleep cycles.
Nap timer
The three nap lengths that work, and why 40 minutes is the worst one.
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How to set an alarm in your browser
- Choose the timeType the hour and minute, then pick AM or PM. If the time has already passed today, the alarm is set for tomorrow.
- Pick a sound and test itPress Test the sound once. This confirms the volume is right and unlocks audio playback in your browser.
- Decide how hard it should be to stopLeave the maths challenge on if you routinely switch alarms off in your sleep. Turn on the gradual fade if you want a softer start.
- Press Start alarmThe panel switches to a live countdown and the browser tab title shows the time remaining, so you can check it from another tab.
- Leave the tab openKeep the device plugged in and awake. Set a second alarm elsewhere if missing this one would genuinely matter.
If a browser tab is not enough
A web page cannot vibrate your mattress or survive a power cut. For anyone who has slept through everything, a physical clock is the honest answer. These are the ones worth the money.
Paid links. We earn a commission if you buy through the links below,
at no extra cost to you. It does not affect what we recommend. Full disclosure.
Best for heavy sleepers
Sonic Alert Sonic Bomb SBB500SS
A 113 dB alarm plus a bed shaker you slide under the mattress. The combination is why it is the default recommendation for people who sleep through everything else.
- 113 dB adjustable alarm
- Wired bed shaker included
- Pulsing strobe light
- Battery backup for outages
Typically $45–$55. Paid link — we may earn a commission at no extra cost to you.
Budget bed shaker
Loud Alarm Clock with Bed Shaker
Most of the Sonic Bomb's waking power for less money, with a large dimmable display and USB charging built in.
- Up to 120 dB
- Vibrating pad for the pillow
- Large dimmable LED numbers
- USB charging port
Typically $35–$45. Paid link — we may earn a commission at no extra cost to you.
Best sunrise clock
Hatch Restore 2
A sunrise lamp, sound machine and clock in one. The light ramp starts before the sound, which is the part that actually changes how waking feels.
- Gradual sunrise light
- Large sound library
- App-controlled routines
- Phone-free bedside design
Typically $150–$180. Paid link — we may earn a commission at no extra cost to you.
Best phone-free design
Loftie Alarm Clock
Built specifically so the phone can leave the bedroom. Two-phase alarm, curated audio, no feed to fall into at 1am.
- Two-phase gentle wake
- Sleep sounds and breathwork
- Wi-Fi updates
- Blackout display mode
Typically $150–$200. Paid link — we may earn a commission at no extra cost to you.
Why waking up is hard
The reason you sleep through alarms is not weak willpower. It is a measurable physiological state, and understanding it is most of the fix.
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Common questions
Will the alarm still ring if I switch to another tab?
Yes. It runs in the background of the same browser, so you can work in other tabs and it will still sound. What it cannot survive is the tab being closed, the browser being quit, or the device going to sleep. While an alarm is armed we request a screen wake lock, which stops most laptops from dimming and suspending the page, but power settings can still override it.
Why won't the sound play?
Browsers block audio until you interact with the page, which is deliberate and applies to every site. Pressing Test the sound or Start alarm counts as that interaction and unlocks audio for the session. If you still hear nothing, raise your system volume, check the tab is not muted (right-click the tab), and make sure output is going to the speaker you expect rather than a disconnected headset.
Can I use this to wake up in the morning?
People do, and it works if you set it up properly: plug the laptop in, disable sleep in your power settings, keep the lid open and the tab in front, and turn the volume well up. Because a web page stops running when the machine sleeps, we would always tell you to set a second alarm on a device that is designed for it. Treat this as your loud primary and your phone as the backup, or the other way round.
Do I need an account?
No. There is nothing to sign up for and nothing to install. Your alarm time, label, sound and preferences are stored in your own browser using local storage, on your device only. Clearing your site data removes them.
Is it really free?
Yes, and it stays that way. The site is paid for by advertising and by a small commission when someone buys a physical alarm clock through one of our links. You are never asked to pay and there is no premium tier hiding the useful features.
What is the maths challenge for?
Sleep inertia makes you capable of switching an alarm off without ever forming a memory of it. A task that requires real cognition — even simple arithmetic — is much harder to complete while still asleep, so it produces a genuine wake rather than a reflex. It is the same principle behind the most successful alarm apps, and you can switch it off if you do not want it.