BUILD
An Android workout app designed and built with AI in 3 months
I designed & developed BUILD, an Android workout tracker shipped with AI as a coding partner in the same window as a paid subscription.
Product
BUILD
What I did
Product design
Android development
AI-assisted engineering
Technologies
Kotlin (Android)
Figma (Design)
Cursor AI (Assistant)
Supabase (Database)
Duration
Q4 2025 – ongoing
Problem
I was paying for a workout app I wanted to replace
I was subscribed to another workout app and wanted to stop paying for it. Rather than bounce between tools, I set a hard constraint: learn enough Kotlin and build my own app in three months, the length of my remaining subscription.
That deadline forced a practical approach. I leaned hard on AI as a build partner, not just for code snippets, but to learn Android patterns, debug issues, and ship a product I would actually use at the gym.
Project goal
How might AI accelerate learning Kotlin while still producing a workout app reliable enough to replace a paid subscription?
Solution
BUILD is a native Android app for creating workouts, logging lifts in real time, and reviewing exercise details without the clutter of a subscription product.
AI was central to the process. I used it to translate design intent into Kotlin, unblock unfamiliar Android APIs, and keep momentum when I hit gaps in my experience. I still owned the product decisions: what to ship first, how the flows should feel, and when the experience was good enough to cancel the other app.
In three months I had a working Android product I still use for every workout.
The result is a personal training companion focused on speed in the gym: create a plan, run the session, and dig into exercise details when you need them.
Current designs
Core flows I use every training day
Create workout
Build a session quickly by assembling exercises into a workout you can reuse. The flow is optimized for planning before you hit the floor.
Active workout
Log sets while you train with a focused, one-handed friendly experience. The goal is staying present in the gym instead of fighting the UI.
Exercise details
Open any exercise for clearer guidance mid-session, so you can adjust form, load, or targeting without leaving the workout flow.
Metrics
Personal training metrics tracked in BUILD 2025:
175
Workouts completed since Dec 2025
2,600
Lifts logged
10 lbs
Muscle gained while training with BUILD