Freelance Full-Stack Developer - Health-Tech App (Remote)

We are building a health-tech app for athletes and fitness enthusiasts. The front-end is already built (HTML/JS, deployed on Netlify). We are now developing Version 2 and need a backend developer to build the infrastructure. Scope of work: • Garmin Health API integration — OAuth 2.0 authentication, automated pull of HRV, sleep score, sleep duration, body battery into the app • User authentication system — sign up, login, password reset (Firebase Auth or Supabase preferred) • Cloud database — store user profiles and session logs with sync across devices (Firestore or Supabase) • REST API or serverless functions to connect front-end to Garmin and database • Push notification support Tech stack preference: • Backend: Node.js or Python (FastAPI) • Database: Firebase / Supabase / PostgreSQL • Hosting: Netlify Functions, Vercel, or similar serverless • Front-end is vanilla JS — no framework required You should have: • Experience with third-party health/fitness API integrations (Garmin, Fitbit, Strava, or similar) • Solid understanding of OAuth 2.0 and REST APIs • Experience with Firebase or Supabase • Portfolio of at least 2 completed full-stack projects • Good English communication — you will work directly with the founder Engagement: • Freelance / project-based • Estimated scope: 6–10 weeks • Remote — open to candidates globally • Budget: negotiable based on experience and proposal To apply, send: 1. Brief introduction and relevant experience 2. 2 examples of previous API integration work 3. Your estimated timeline and budget for the scope above Please do not apply if you do not have direct experience with health data APIs or OAuth integrations.