The Technology Behind Tomatoro — and Why It's So Accurate

A pomodoro timer has exactly one job: count down honestly. It sounds trivial, yet most timers built for the browser lose seconds — sometimes minutes — without ever telling you. Tomatoro is built so that doesn't happen. Here's why.

Why most browser timers drift

The naive way to build a countdown is to subtract one second every second:

start at 25:00, then every tick take one off.

The trouble is that the browser never promises those ticks land exactly one second apart. To save battery and CPU, browsers throttle timers in background tabs, coalesce them, and pause them entirely when your laptop sleeps or your phone locks. A timer that counts ticks has no way to know how much real time went by while it wasn't running — so it silently falls behind.

If you've ever switched tabs for "a few minutes" and come back to a pomodoro that's barely moved, you've seen tick-drift in action.

Tomatoro counts real time, not ticks

Instead of decrementing a number, Tomatoro records when your session started and derives the time left from the actual clock:

• It anchors each session to a real timestamp the moment you press start.
• Every render it asks "how much time has actually elapsed since then?" and shows the remainder.

Because the answer always comes from the real clock, drift can't accumulate. Skipped ticks, throttling, a coalesced frame — none of it matters, because the display is recomputed from the truth rather than patched one second at a time.

It re-syncs the instant you come back

When a tab is hidden the browser slows everything down. Tomatoro takes advantage of that quietly: the moment the tab becomes visible — or the window regains focus — it recalculates from the start timestamp. So a timer you left at 18:42 shows the correct time the very first frame you look at it again, not after a catch-up stutter.

Background-safe by design

Because the remaining time is a calculation, not a running counter, your pomodoro stays correct while the tab is in the background, while another app is in front, and while your screen is off. When you return, the number is right.

It survives reloads

Session state is persisted, so an accidental refresh — or the browser quietly discarding a backgrounded tab — doesn't reset your progress. Tomatoro restores the session and, again, recomputes the remaining time from the original start. You pick up exactly where you were.

One honest clock per device

Each device runs its own independent clock. That's deliberate: starting a pomodoro on your laptop shouldn't secretly control your phone. Your history syncs across devices with a free account, but the ticking timer is local and precise wherever you are.

The takeaway

Accuracy isn't a feature you bolt on — it's a consequence of measuring time the right way. By anchoring to real timestamps, re-syncing on focus, and surviving backgrounding and reloads, Tomatoro gives you a number you can actually trust.