Product Engineer - Full-Stack Developer

💡 ABOUT LIFTOFF Our Mission: Making the world a healthier place by gamifying fitness Liftoff is the Duolingo of fitness, empowering anyone to start and stay at the gym so they develop healthier, more powerful habits. We’re a mission-driven team that moves fast, owns the details, and does the work. We’re fully bootstrapped, profitable, and built from zero to $10M+ ARR in under three years. 🌟 ABOUT THE TEAM You'll join the Product team and work closely with the Head of Product, collaborating with Engineering, Design, and Growth Our product is the engine behind everything: retention, monetization, and ultimately revenue. This role is for someone who wants end-to-end ownership over backend reliability and experiment velocity, and loves shipping. 🎯 ABOUT THE ROLE We're hiring a Full-Stack Engineer to ship product features and experiments end-to-end. Your core focus areas: - Feature delivery across the stack in TypeScript, from React Native screens to Supabase data - Polished, correct UI, shipped to the standard of the design, not an approximation of it - Experiment infrastructure and instrumentation - Clean, performant API and data access - Cross-functional shipping with Product, Design, and Growth This is a high-ownership role. You'll take a problem from spec to shipped, work with our existing team/resources, and own the outcome, not just your slice of it. ✅ WHAT SUCCESS LOOKS LIKE - Features and experiments that go out end-to-end without stalling on handoffs - UI that ships pixel-correct and feels right; spacing, states, edge cases, and transitions handled without needing a review pass to catch them - A high-velocity experiment pipeline: clean instrumentation → fast implementation → reliable measurement → iteration - A product that stays fast and stable as usage grows; schema changes land safely, queries stay efficient - Shipped improvements that compound (reusable experiment patterns, better event tracking, faster deploys, fewer incidents) - Strong operating cadence with crisp communication on what's shipping, why, and what it did 🛠️ WHAT YOU’LL DO - Ship features end-to-end - Build the front end in TypeScript with React Native (Expo); typed, readable, and maintainable by the next person - Implement designs faithfully: correct spacing and type, all states (loading, empty, error), and the edge cases the mock doesn't show - Write and run migrations and deploy schema changes safely; keep the data model clean as the product grows - Stay conscious of load and performance - catch the slow query or the runaway request pattern before users do - Ship experiments and instrumentation - Partner with Product/Growth to implement A/B tests and feature flags via Statsig - Ensure every experiment has clean event tracking and reliable data - Build reusable patterns that reduce experiment cycle time - Use data to drive decisions - Instrument events…