Principle Guy
A training platform that adapts every workout to your measured Fitness Level.
Overview
Principle Guy is my own product: a training platform where progress is a measured number, not a guess. It spans a Flutter app as the primary surface, a Next.js marketing site and blog, and a Vue admin console, all on Firebase with native in-app billing. I designed, built, and shipped every layer.
Challenge
Generic training apps ignore where each person actually is. Plans land too hard or too easy, and people drop off in the first weeks.
What I built
I designed a Fitness Level system: every exercise carries ten levels, and server-side auto-progression tunes each session to the user's measured level. The product spans a Flutter app as the primary surface, a Next.js marketing site and blog, and a Vue admin console for authoring, all on Firebase with native in-app billing.
Outcome
Live on the App Store and Google Play with a full subscription and coaching engine. Hundreds of users onboarded and a growing active base.
A Fitness Level that measures you, not the average
Every exercise carries ten levels. Server-side auto-progression tunes each session to the user's measured level, so training is never too hard or too easy. Progress becomes a single number that climbs over time.
Track the whole picture
Calories and macros, weight, sleep, and body composition, all logged in one place and fed back into the plan. The journal is the raw signal the coaching engine reads.
A weekly check-in and real coaching
A curated weekly ritual pulls the key metrics, walks the user through them, and generates a summary a coach replies to. Exception-based coaching that scales without a trainer in every user's week.
An admin console to author it all
Exercises, levels, workout templates, and packages are authored in a Vue admin console, with analytics flowing to BigQuery for cross-surface insight.
The product
Every screen, shipped.
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