🇺🇸

Building CoreHour: A Time-Boxing App Around the 80/20 Rule

Published on

CoreHour — Do less. Achieve more.

​
Introduction

For the past while, Carol and I have been building products together under Aburi Studio, our two-person studio based in Calgary. The first product I want to introduce here is CoreHour — a minimalist time-boxing app built around one idea: the 80/20 rule.

Its philosophy is printed right on the landing page: "Do Less. Achieve More."

​
Demo

​
Why we created this project

Most productivity tools are great at collecting tasks, and terrible at telling you a harder truth: not all tasks deserve your time. A day can be completely full and still accomplish nothing that matters.

The Pareto principle says roughly 20% of your tasks drive 80% of your results. The hard part is seeing which 20% that is — and actually protecting time for it.

We were our own victims: growing task lists, stalled important work. So CoreHour asks you to do just three things: set your focus, timebox your day, and track your focus hours.

​
Key Features

  • Plan your day visually: drag and drop tasks into a timeline of 30-minute blocks, with color-coded categories, so you can see your entire day at a glance.
  • Mark what's critical: flag your high-impact tasks, and track how much of your time goes to them versus busy work.
  • Automatic conflict handling: overlapping time boxes get trimmed, split, or merged automatically — no manual shuffling.
  • Learn from your own data: a daily focus-hours goal, streaks, and a weekly breakdown of where your hours really went.
  • Stay out of your way: a clean, thoughtfully crafted interface with light and dark modes.

One detail I especially like: the streak has three states, not two. Because CoreHour is a planner, qualifying days count backwards and forwards — future days can already be planned. If today isn't planned yet but yesterday kept the streak alive, you're in a "planning" state and the UI nudges you instead of showing a broken streak.

That's it. No project management ceremony, no team features you'll never use. It's a daily planning tool for one person: you.

​
Technologies

Under the hood, CoreHour is a Next.js web app and an Expo-based iOS app sharing one Supabase backend, with subscriptions handled by RevenueCat. I'll save the deeper engineering stories for future posts.

​
Where it's at

CoreHour is live at corehour.app, with a 7-day trial that needs no credit card. An iOS app is in the works.

If time boxing or the 80/20 rule ever appealed to you, I'd love for you to try it and tell me what's missing.

CoreHour is part of a small family of tools we're building at Aburi Studio around time and money — alongside FireFree, a FIRE planning app (read about it here), and DailyWage, a real-time salary counter (read about it here).

If you have feedback, find me on X or email me — I read everything.