Strength Tracker
My own training app: log workouts on phone and laptop, even without signal, with concrete advice every week.
Who it is for
My training partner and me. I still use it every week.
The problem
Training apps are often English-only, work poorly without internet, or do not let two people log at the same time. I wanted one app that shows the same on phone and laptop, simply works in a gym without signal, and tells me after each week which weight to use next time.
What I built
Strength Tracker is a web app you install like a regular app. You log sets, weights and reps, alone or together with your training partner. Everything is stored on your own device first and then syncs to your other devices by itself. It includes a library of over a hundred exercises, a 3D figure that shows which muscles you trained this week, and weekly advice for your next weights.
What it delivers
Works offline in the gym and syncs as soon as there is signal again.
Train together: several profiles in one session.
Concrete weight advice every week, based on the week before.
Installable on phone and laptop, straight from the browser.
Under the hood
Data stored locally first, then synced in real time between devices.
A custom service worker, so the app also opens without internet.
Rebuilt in ten steps into a fast app that only loads what you need, with 110 automated tests.
The hardest part
On a new device the app stayed empty while the data did arrive: the active profile pointed to a profile that only existed locally. Now the app picks a valid profile automatically after merging, and shows a clear message when syncing gets stuck somewhere.
Built with
- React
- TypeScript
- Vite
- Tailwind CSS
- Supabase
- Three.js