Building a Calmer Focus Timer: What I Learned from Designing a Tiny Productivity Tool

I have been working on a small productivity project called Focero.

The idea is simple: a calm focus timer for studying, deep work, writing, coding, and everyday tasks.

At first glance, a timer sounds like one of the easiest things to build. You show a number, count down every second, and play a sound when time is up.

But after working on it for a while, I realized that a good focus timer is less about the countdown itself and more about all the small product decisions around it.

Website: https://focero.com/

A timer should not feel like another distraction

Many productivity tools accidentally become another thing to manage.

They add dashboards, graphs, accounts, streaks, gamification, task systems, notifications, calendars, and settings before the core experience feels calm.

For Focero, I wanted the opposite:

• open the page
• choose a focus rhythm
• start
• keep working

The product should disappear into the background once the session begins.

That sounds simple, but it changes how you design the whole interface.

The core interaction should be obvious

For a focus timer, the user should understand the page within a few seconds.

The most important elements are:

• the remaining time
• the current mode
• the start / pause / reset controls
• the selected focus rhythm

Everything else has to earn its place.

I tried to keep the main screen centered around one large timer. Secondary features should support the session, not compete with it.

Presets matter more than endless options

A custom timer is useful, but most users do not want to configure everything from scratch.

So I focused on a few common rhythms:

• 25 / 5 for classic Pomodoro
• 50 / 10 for deeper work
• custom sessions for users who already know what they want

This keeps the product flexible without turning the first experience into a settings page.

Local state is enough for the first version

One product decision I like is avoiding accounts in the early version.

For many simple tools, an account is not the first problem to solve. A user does not need to sign up just to start a focus session.

Local state is enough for things like:

• selected timer mode
• custom focus duration
• custom break duration
• basic user preferences
• session recovery

This keeps the product lightweight and reduces privacy concerns.

The tricky part is reliable time

A common mistake is treating a timer as just setInterval.

js
setInterval(() => {
  remainingSeconds -= 1
}, 1000)