Jim Coach. An AI personal trainer in your pocket — form checked, reps counted, no gym membership required.
Jim Coach is a mobile AI fitness assistant built to eliminate the three biggest barriers to working out: not knowing what to do, not knowing if you're doing it right, and not being able to afford someone who does. Using computer vision and multimodal AI, it watches your form in real-time, counts your reps, and coaches you — like a personal trainer, but on your phone.
100+
Alpha Users
via Reddit launch
30fps
Pose Tracking
real-time on device
6wks
To Validation
concept to product
#1
Form App
CV-based on App Store
01 — User Research
What barriers do people face to working out?
I conducted a survey of 15+ people from my gym. I wanted to understand the friction points. The most common words have been visualised below by frequency.
02 — Market Research
Identifying the 'Form Gap' in the App Store
Top fitness apps did most things well. But a major gap emerged: no app could ensure exercises were performed with correct form — the single feature that determines results and prevents injury.
03 — Skills Applied
End-to-end capability required
04 — Tech Stack
Tools that built Jim Coach
Framework
Next.js
Framework
React
Styling
TailwindCSS
Animation
Framer Motion
AI
Google Gemini
AI
Computer Vision
Design
Figma
Language
TypeScript
05 — Process
From Gym Survey to App Store
01
User Research
Surveyed 15+ gym-goers to map friction across knowledge, motivation, cost, and time.
02
Market Research
Semantic analysis of top App Store fitness apps to identify the 'Form Feedback Gap'.
03
User Flow
Designed an end-to-end workout journey from onboarding to real-time CV coaching loop.
04
Branding
Created the JC logo (an apostrophe) and a stern-but-friendly typographic system for coach-like authority.
05
Development
Built the web Alpha using NextJS, integrating multimodal AI for voice and pose estimation.
06
Alpha Launch
Seeded Reddit with early access. 100+ users provided the data to iterate toward App of the Day.
06 — Lessons Learned
Distribution is the Final Boss
Early validation was strong, but scale didn't come from individual user acquisition — it clicked when I discovered the efficiency of nodes of distribution. Personal trainers weren't just users; they were multipliers. Each PT carried a roster of clients who had a real, immediate need for Jim Coach.
To understand this problem properly, I went all the way in: I got a job as a personal trainer. Living the PT experience gave me an insider's perspective on how coaches think about client progress, what tools they trust, and exactly where Jim Coach could slot into their workflow.
12+
Personal Trainers Approached
In local gyms & studios
20–40
Avg. Clients per PT
Immediate distribution nodes
Mobile
Next Step
Native camera & notifications
Jim Fitness
jim.coach