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Online Alarm Clock — Free Browser Alarm with Night Dim Mode

A Browser Alarm Clock, No App Required

Set a wake-up time, pick a sound, and arm it — all in a browser tab, with no download and no account. Built for a quick alarm on a laptop or tablet, not as a replacement for your phone's alarm when you need it to survive a locked screen.

Where People Use It

Waking up without installing an app

Set the time, arm it, leave the tab open — no App Store account, no permissions prompt, no ad-supported alarm app to dig through first.

A quick daytime alarm

Set it for any time of day, not just the morning — a reminder to leave for an appointment, check something in the oven, or stop working.

Night use without a bright screen

Dim the display for night use so the alarm isn't the brightest thing in the room while you fall asleep.

A backup to your phone's alarm

Set the same wake-up time on a laptop or tablet next to the bed as a second alarm, in case one device gets silenced or the battery dies.

How to Use

Four steps from setting the time to it ringing.

Set the time

Enter hours and minutes, and switch between 12-hour and 24-hour format in Settings.

Arm it

Tap Alarm Armed. This first tap also unlocks sound in the browser — required once per session before the alarm can play automatically.

Pick a sound

Choose from three alarm sounds — Happy Bells, Uplifting Flute, or Classic Short — each with a one-tap preview before you commit.

Snooze or stop when it rings

Snooze adds 5 minutes; Stop re-arms the alarm for the same time tomorrow. Left ringing, it stops on its own after 10 minutes as a safeguard.

Features

What you're actually getting, feature by feature.

Three alarm sounds

Happy Bells, Uplifting Flute, and Classic Short — real recorded tones, not a single fixed beep, each previewable before you pick it.

12 / 24-hour format

Switch formats without losing the time you've already set.

Night dim mode

Dims the display for use at bedside without a full-brightness screen glowing in a dark room.

Fullscreen mode

Clear the browser chrome away so the time is the only thing on screen.

Keep screen on

Keeps the screen awake while armed, so the alarm can't be missed because the display went to sleep.

Color themes

Pick from the same LED color set as the rest of the site's clocks, saved locally for next time.

FAQ

The questions that come up most about this tool.

Will the alarm still ring if I close the tab or lock my phone?

No — this runs in the browser tab, so the tab needs to stay open and the screen needs to stay on for the alarm to fire. It's not a substitute for your phone's native alarm if you need it to survive a locked screen.

Can I change the alarm sound?

Yes — three sounds under Alarm Sound in Settings (Happy Bells, Uplifting Flute, Classic Short), each with a one-tap preview so you can hear it before arming.

What happens if I don't stop the alarm?

It rings on a loop for up to 10 minutes as a safeguard against endless ringing, then stops on its own. Tap Stop to re-arm it for the same time tomorrow, or Snooze for 5 more minutes.

Why does it ask me to tap something before the alarm can play?

Browsers block audio from starting on their own until you've interacted with the page at least once. Arming the alarm doubles as that first tap, so sound is unlocked well before it needs to fire.

Does this work on mobile?

Yes, in a mobile browser — but the same rule applies: the tab has to stay open and the screen has to stay on, which is more battery-hungry than a native phone alarm.

From the Blog

Need a plain countdown or a stopwatch instead of a wake-up time? See the Online Timer. Working in focus sprints instead? See the Pomodoro Timer.