About Online Alarm Clock
Online Alarm Clock is a free, browser-based alarm clock. Set a time, keep the tab open, and it can ring through your browser. No app or account is required. Timers, countdowns, a stopwatch, and a world clock are here too.
Why I built this
I built this because I wanted a simple alarm clock on my computer. I did not want to create an account, install an extension, or work through a download prompt just to set a time. I wanted to choose 6:40 AM, leave the page open, and get on with my evening.
This site is centered on the clock and the tools around it. Set an alarm, start a timer or stopwatch, use a countdown, or check another city's time without signing in. I run the site myself and use it when I am at my computer and need a reminder.
I maintain the site and fix issues I find. Browser alarms have real limits, so this page explains them up front. If something goes wrong, tell me your browser, device, and what happened.
How the alarm actually works
This page schedules and plays the alarm in your browser. With permission, it can also show a browser notification as a secondary alert; it cannot start your computer or browser. Keep the page open and device awake. Another tab is usually fine, but browser throttling may delay the alarm.
Before relying on an alarm, check the things that most often prevent people from hearing it:
- Keep this page open. Closing the tab or browser stops the running alarm, even though its saved settings may still be in this browser when you return.
- Keep your device awake. A sleeping or powered-off device cannot be woken by this website.
- Preview the sound, allow browser audio, and check system volume. A muted tab or device can make an alarm seem broken. Notifications also need permission and may be blocked by system settings.
- Load the page and set the alarm before relying on it.
For something you cannot afford to miss, such as a flight, interview, or medication, set a backup alarm on a phone or dedicated alarm clock. A browser page cannot guarantee delivery of a time-critical alert.
Does the alarm work in another tab?
It can continue, but browser throttling may delay it. An allowed notification may add an alert. Keep the device awake and test your setup.
Can it wake my sleeping computer?
No. The browser page cannot wake a sleeping or powered-off device.
Why did I not hear the alarm?
Check that the page is open, the device is awake, sound is not muted, and browser audio is allowed. Background throttling may delay playback; notifications may be suppressed.
Are browser notifications guaranteed?
No. Notifications are optional and require permission. Your browser or operating system may suppress them, and they cannot wake a sleeping device. Treat them as a secondary signal, not a guaranteed alarm.
Can I set a repeating alarm?
Yes. The alarm supports one-time, daily, and weekday schedules. The page still needs to be open and the device awake when the alarm is due.
Are my alarm settings saved?
Schedules and presets stay in this device's browser storage; they do not sync to other devices or browser profiles. Uploaded custom sounds are stored here too.
Is Online Alarm Clock free to use?
Yes. You can use the browser-based alarm and time tools without paying, installing an app, or creating an account.
What it is good for — and what it is not
A good fit
Waking up from a short nap while you are nearby, keeping a meeting on schedule, timing something in the kitchen, reminding yourself to leave for an appointment, tracking a study block, or any other reminder while you are at your computer.
Not the right tool
Do not rely on it if the device may sleep, shut down, lose power, or lose its browser session. It is not a replacement for a phone alarm or a dedicated alarm clock for a wake-up you cannot miss. It also cannot guarantee exact timing while a browser tab is in the background.
Need to count down from a duration instead of setting a clock time? Countdown Timer or use the Online Timer.
Your data
No account is required. Alarm schedules, presets, and any custom sound file you choose are stored locally in this browser on this device. Read the privacy policy for details about contact messages and optional analytics.
Contact
Found a bug, had an alarm fail to play, or want to suggest a feature? Send a message through the contact page or email me at [email protected].