Interval timer (Tabata / HIIT)
Work and rest rounds with a different sound for each switch. Tabata is 20 seconds on, 10 off, 8 rounds; set anything you like.
How it works
Set the work and rest lengths and the number of rounds, or tap a preset. A short countdown gets you into position, then the timer alternates work and rest with a beep three seconds before each switch and a different tone for work and rest, so you can follow it without looking. The round counter shows where you are; the final round ends with the full alarm sound.
Tabata is the original protocol: eight rounds of 20 seconds all-out and 10 seconds off, four minutes total. EMOM ("every minute on the minute") is a 60-second work interval with no rest; do the set, rest for whatever is left of the minute.
See also the workout timer for single blocks and the stopwatch for laps.
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.
Can I hear the switches without looking at the screen?
Yes. Three short beeps count down the last seconds of every interval, then a high tone starts work and a low tone starts rest.
Does the timer keep running if the screen locks?
The timer is measured against the clock, so it stays accurate, but a locked phone may not play sound. Keep the screen on (the page asks the device to stay awake) or use a laptop.