Nap timer
A nap timer with the two lengths that actually work: 20 minutes for a power nap that stays in light sleep, or 90 minutes for a full sleep cycle. Anything between tends to leave you groggy.
How to use the nap timer
Lie down as soon as you press Start; the 20 minutes includes drifting off. Choose a gentle sound with the volume ramp so waking is not a jolt, and use night mode if the room is dark. For a nap that ends at a fixed clock time, use the alarm instead.
Other timers: interval / Tabata timer, Pomodoro, stopwatch, any length.
Questions
Will the alarm ring if I close the tab or the laptop?
No. No website can ring after the browser is closed or the computer sleeps. Keep this tab open, plug in, and the clock keeps the screen awake for you. The Ready-to-ring check under the clock shows what is set up correctly.
Does it work on my phone?
Yes on Android while the tab is open (behind other tabs is fine). On iPhone the page must stay in the foreground because Safari does not let web pages play sound from the background. Add it to the Home Screen for a full-screen bedside clock.
Is it loud enough for heavy sleepers?
Pick Loud buzzer or Siren, set the volume slider to full, and switch on the sums-to-stop option in Settings so the alarm cannot be dismissed half asleep. The sunrise light brightens the screen before the alarm too.
Can I use my own sound?
Yes. In Settings, choose an MP3, WAV or OGG file. It is stored in this browser only and never uploaded. There are also 60 built-in sounds, from a twin-bell alarm clock and a rooster to an air horn and a music box, on the sounds page.
What do the sleep sounds do?
Rain, brown noise, white noise, fan and ocean are generated in the browser and play until the alarm, then fade out as it rings. They keep the tab active through the night.
Does it need an internet connection?
Only to load the page the first time. Alarms, sounds, the sleep calculator and the sunrise math all run on your device, and the page works offline once it has been opened.
Is anything stored or sent?
Alarms and settings are saved in your browser's local storage. Nothing is sent to a server, and there is no account.
Does the nap timer keep running if I switch tabs?
Yes. It measures time against the device clock, so a background tab still ends on time and rings when it does; on desktop the sound plays from the background too.
Can I use it on a phone?
Yes. Keep the page open; on iPhone it must stay in the foreground to play sound.