GymApp is a gym operations platform that brings member services and day-to-day staff workflows into one connected product. The member-facing mobile app gives people a place to browse classes, view class details, manage bookings, check payment information, receive notifications, and access check-in and entry history.

For gym teams, the staff portal brings key operational tools together, including a dashboard, member records, membership plans, class management, and check-in history. A dedicated scanner supports the in-person check-in flow, connecting the digital experience with the front desk.

The project includes separate mobile and web experiences backed by a shared API, with access tailored to each user’s role. The goal is to make routine gym tasks easier for members while giving staff a clear, practical way to manage daily operations.

GymApp was built and debugged entirely on Replit: the Expo member app, the staff portal, the front-desk scanner and the Express API run as separate Replit artifacts in one pnpm workspace, backed by Replit's built-in PostgreSQL, with the QR signing key kept in Replit Secrets.

I directed Replit Agent through scoped written briefs and a replit.md rulebook (integer-cent money, one implementation per business rule, transactional bookings, a role check and an integration test for every endpoint), and required pasted test and build output before any task counted as done.

On the debugging side, I merged two conflicting QR check-in systems into one shared service, fixed a port clash between the mobile build and the workspace's design preview that was breaking the root build, made all three clients check logins with the server and fail closed, and replaced an N+1 query on the class schedule with a constant number of queries.

It ships with 92 integration tests running against a throwaway Postgres database, including simultaneous bookings for the last seat and tampered or expired QR codes.