The HIIT timer
you don't install.

A gym TV. A hotel laptop. A phone you borrowed.
Open the same URL, and that's it.

Use it now How it works
FreeNo adsNo accountWorks offlineEnglish / 日本語
Demo

Trying it beats reading about it

The screen below is not a video — it's the real timer. Pick a preset and hit start.

Like it? Open it full screen →

Features

What it does

Four presetsTabata 20s/10s ×8, Classic 40s/20s ×10, Boxing 3min/1min ×3R, Sprint 30s/30s ×6×2
Everything adjustablePrep, work, rest, rounds, sets and rest between sets — tuned in 5-second steps
Readable by colour
Prep is amber, work is red, rest is green, set-rest is blue. The whole screen changes, so it reads from across the room with the phone on the floor
Beeps and vibrationA countdown for the last 3 seconds and a cue at every phase change, plus vibration on supported devices
The screen stays onThree layered wake-lock techniques keep the display awake while the timer runs
Works offlineAfter the first visit, the whole app (~31KB) is stored on your device and starts with zero signal
Share settings as a linkTurn your workout into a URL and send it to a training partner. They just open it — no sign-up
English / JapaneseSwitch languages in the top-right corner; the choice is remembered on your device
How to use

How to use it

Open it

Go to timer.nexus-code.studio in any browser. Nothing to install, nothing to sign up for.

Pick or tune

Tap a preset, or shape your own workout with the −/＋ steppers. The total time shows at the top.

Start

While running, tap anywhere (or press Space) to pause. Skip and Stop are always available.

Add it to your home screen (recommended)

It launches full screen from an icon and looks and behaves like a native app.

iPhone / iPad

Open it in Safari → Share button → "Add to Home Screen" → Add. (Chrome on iOS can't do this.)

Android

Open it in Chrome → menu (⋮) → "Add to Home screen" or "Install app".

Send a workout to someone

Press "Share these settings as a link" under the Start button and the current configuration is copied as a URL.

Example: timer.nexus-code.studio/?w=45&r=15&rd=10 opens pre-set to 45s work / 15s rest × 10 rounds. A coach can text the day's intervals straight to a client.

At the gym

Using it at the gym

It works in the basement. Open it once anywhere with signal, and from then on it makes no network requests. Dead zones and locker rooms don't matter.

It works on the wall. Open the URL in a smart TV's browser or on a monitor hooked to a laptop and it becomes a class clock the whole room can read. No special hardware.

Honest limits

What it can't do — said upfront

On iOS it stops if the screen turns offThat's a browser limitation we can't work around. In exchange, the timer suppresses sleep while running, and if it ever does stop, it catches up to real elapsed time the moment you return — phases never drift. If your screen still sleeps: Settings → Display & Brightness → Auto-Lock → Never.
Your music volume may dipRunning it alongside a music app can lower the music's volume. We're investigating; this page will say so when it's fixed.
No workout historyNothing is stored by design, so there is no log of past sessions.
Why free

Counting to four minutes shouldn't cost a subscription

Plenty of interval timer apps let you run a few workouts and then show a paywall. This one is built the opposite way: it collects no account and no email, so there is structurally nothing to hold hostage later.

The mechanics are just as simple. A small set of files runs entirely on your device, so if this site vanished tomorrow, the copy stored on your device would keep working.

It's built by one person. If you like it, a coffee's worth of support keeps it going.

FAQ

Fair questions

There are hundreds of free interval timers. Why this one?

Because opening it costs nothing. No store page, no download, no notification prompt — and it works in places an app never can: the TV on a gym wall, a hotel laptop, a borrowed phone. If it's not for you, close the tab and nothing is left on your device.

You'll paywall it once it gets popular, right?

Fair suspicion — that's the most common one-star review in this category. But this timer takes no account and no email, so there's nothing to hold hostage later. Development runs on optional tips only.

Does it stop when the screen turns off?

On iOS, yes — we won't hide that. It's a browser limitation. In return the timer suppresses screen sleep three different ways, and if it ever does stop, it snaps forward to real elapsed time when you return, so you're never "three rounds behind".

Does it work with no signal?

Yes. Open it once with a connection and everything is stored on your device. Add it to your home screen and it launches from the icon even in airplane mode.

It's one person's side project. What if it shuts down?

There's no server to shut down. A small set of files runs entirely on your device, and once it's stored there, it keeps working whether or not this site does.