Founding Full-Stack iOS Engineer

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., * 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

• 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

• 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