Founding Full-Stack iOS Engineer

About the Role This is a founding engineering opportunity at a Y Combinator Spring 2026 consumer wearable startup operating at the intersection of emotional intelligence and computational neuroscience. The company is building a wearable device that measures and surfaces real-time emotional-state data — think energy, mood, and focus — derived from a proprietary inference model processing over 150 audio and biometric signals. Prototypes are already on users' wrists. As the Founding Full-Stack iOS Engineer, you will own the companion iOS app end-to-end — the primary surface through which users experience and act on their emotional data. This is a high-ownership, high-impact role with a direct line to the founding team and a clear path to leading the engineering org as the company scales. What You'll Do Own the companion iOS app from architecture through to polished, consumer-grade delivery Integrate and surface real-time emotional-state outputs (e.g. energy, mood, focus scores) from the backend inference model into the app experience Build and iterate on UI/UX that makes complex neuroscience outputs intuitive and actionable for everyday users Collaborate closely with research and hardware to shape the full product experience Lay the technical foundations and engineering culture as an early founding hire What We're Looking For Required Strong, proven experience shipping consumer iOS apps (Swift) — a few years minimum; not a role for recent graduates Full-stack capability: comfortable owning both the mobile layer and relevant backend/API integration Track record of building polished, high-quality consumer-grade mobile experiences Ability to move fast and operate with high autonomy in an early-stage environment Nice to Have Experience with health, fitness, or wearable app ecosystems (HealthKit, CoreMotion, Bluetooth LE, etc.) Interest in biometrics, emotional intelligence, or computational neuroscience Prior founding or very early-stage startup experience Compensation & Benefits Salary: ~$150,000 USD (San Francisco) / ~£75,000 GBP (London) Equity: Up to 1–2% — meaningful founding-level ownership Seed-stage company with angel and strategic investment; recently completed a funding round Visa sponsorship: Not available for new sponsorships; visa transfers are welcome Location Primary location is San Francisco, CA, with flexibility for London, UK or remote candidates depending on experience and fit. The team is small (5 people) and moves quickly — proximity to the founding team is valued.