Next Gym

A production-grade, multi-tenant SaaS platform designed, architected, and built almost entirely through AI-assisted development as a solo developer.

Next Gym is the most technically ambitious project I have built: a full-stack SaaS platform spanning four deployed sub-applications and a shared Turborepo monorepo. It was developed primarily using Claude and Cursor as AI coding assistants, which dramatically accelerated the scope and quality of what I was able to ship alone.

The platform covers the complete lifecycle of running a gym business: member management, class scheduling and QR check-in, multi-product billing via Stripe, document compliance and digital signing, multi-location support, personal training management, and a React Native mobile app with biometric authentication. Each of the four sub-applications shares a tRPC v11 API layer, a Drizzle ORM schema over Supabase PostgreSQL, and a cross-platform @gym/shared package.

AI-driven development was not just a productivity tool. It was the core methodology. AI tools designed the database schema, scaffolded all 27 tRPC routers with end-to-end type safety, implemented complex multi-tenancy and RBAC patterns, wrote React Email templates, and maintained consistency across a large codebase.