Founding Engineer (Potential CTO)

About the Role This is a rare Founding Engineer (potential CTO) opportunity at a seed-stage, AI-native digital health startup focused on nervous system repair and chronic disease management. You'll be the second technical voice at the company — the person who turns a bold product vision into a production-quality AI mobile experience, and who defines the engineering culture and stack for the next decade. You'll own the full technical journey: from shipping the first end-to-end AI coaching experience in a React Native app, to architecting the model and feedback loop that powers a real-time nervous system training coach using wearable biosignal data. This role is in-person in Montreal, San Francisco, or New York City, and is central to everything the founding team builds. What You'll Do Serve as Founding Engineer and potential CTO, owning technical direction and day-to-day execution. Ship the AI coaching product v1 end-to-end — from a React Native mobile app to Claude-backed inference and wearable integrations. Architect and build an AI-powered nervous system training coach, including model design, prompt engineering, tool use, and evaluation pipelines. Translate biosignals (HRV, breath, motion, PPG) into a real-time personalized coaching layer. Build and maintain AI-powered QA and testing pipelines to enable safe, fast daily shipping. Own full-stack decisions across frontend, backend, infrastructure, and AI-native layers. Integrate iOS/HealthKit and wearable platforms (e.g. Apple Watch, Oura, Whoop, EEG headbands). Collaborate closely with the founding team on-site in Montreal, SF, or NYC. What We're Looking For Dealbreakers (must-haves): Production experience shipping and operating Claude or other frontier LLM-based systems, including prompts, tool use, and evals. Willingness and ability to work in-person in Montreal, San Francisco, or New York City. 3+ years in mobile/full-stack engineering with a track record of delivering 0→1 consumer mobile apps to real users. Required skills & experience: Deep fluency in React Native with end-to-end ownership of the mobile lifecycle (build, release, debug, monitor, iterate). Experience with AI-native infrastructure where AI functions are integrated across all layers — not bolted on. Backend development in Node.js or Python with PostgreSQL and modern infra (Vercel, Fly, Render, or similar). Ability to move fluidly across the full stack (frontend, backend, infra, AI) with minimal handholding. Hands-on experience with HealthKit, wearable APIs, or real-time biosignal data (HRV, PPG, motion). Founder mindset: comfortable making hard tradeoffs, operating with high autonomy, and building from zero. Nice to have: Experience building AI-powered testing or evaluation pipelines. App Store shipping experience — a consumer mobile app with real, active users. Background or genuine interest in nervous system science, somatics, neuroscience, or trauma research. Prior experience as the first or founding engineer at an early-stage startup. Compensation & Benefits Base salary: $170,000 USD / year Early-stage equity commensurate with founding-team scope High-impact, high-ownership role with a direct path to CTO Visa sponsorship is not available for this role. Location This is a fully on-site role. The founding team works together in person across New York City, San Francisco, or Montreal. Candidates must be able to commit to in-person collaboration at one of these locations.