Is the HIIT timer really free?

Yes. There's no paid version, no trial and no ads. Every feature is on this page.

Do I need to download an app?

No. It runs in any modern browser on a phone, tablet or computer. If you want an icon, use your browser's "Add to home screen".

Does it work offline?

Yes, once it's loaded over the internet once. After that it opens without a connection.

Will it keep my screen on?

On browsers that support the Screen Wake Lock API (most current phone and desktop browsers), yes, while the timer is running.

Free HIIT timer

An interval timer that runs right here in your browser. Set your work and rest, press start, and it counts you through every interval with beeps and a countdown, showing the move you're on and the one coming next.

Open the timer Build a workout first

Start one now

Tabata 3:50 · 20/10s · High knees
20 on, 10 off, 8 rounds of one move
Start Edit
Beginner 30/30 11:30 · 30/30s · 6 moves ×2
Half work, half rest, no jumping
Start Edit
Classic 40/20 15:40 · 40/20s · 8 moves ×2
The most common HIIT split
Start Edit
Hard 45/15 15:45 · 45/15s · 8 moves ×2
Short rests, for when 40/20 feels easy
Start Edit

What the timer does

Work, rest and a get-ready countdown, each set in seconds.
Beeps for the last few seconds of every interval, so you don't have to watch the screen.
Shows the move you're on and the one coming up, with an animated figure from two angles.
Keeps your screen awake while it runs, on browsers that allow it.
Big enough to read from across the room. Cast it to your TV or plug in a laptop, then press Full screen.
Space to start or pause, the right arrow to skip, and tap the strip to jump to any interval.
Repeats: run the whole list as a circuit, or do sets of each move.
Works offline once it has loaded, and you can add it to your home screen like an app.

Which work/rest split to use

20/10 (Tabata): very hard, very short. Four minutes per block of eight rounds.
30/30: a good place to start. Equal rest means you can keep your form.
40/20: the standard. Hard enough to count, enough rest to keep going for 20 minutes.
45/15: for when 40/20 feels comfortable. The short rest is mostly for switching moves.

The builder suggests a split for you based on your goal and level. You can change it either way.

Use your own exercises

Open "Timer settings & workout as text" under the timer and type one exercise per line. Anything from the exercise library gets an animation; anything else still gets timed. Your list stays saved in this browser.

Questions

Is the HIIT timer really free?: Yes. There's no paid version, no trial and no ads. Every feature is on this page.
Do I need to download an app?: No. It runs in any modern browser on a phone, tablet or computer. If you want an icon, use your browser's "Add to home screen".
Does it work offline?: Yes, once it's loaded over the internet once. After that it opens without a connection.
Will it keep my screen on?: On browsers that support the Screen Wake Lock API (most current phone and desktop browsers), yes, while the timer is running.