Founding Full-Stack iOS Engineer

<h3>About the Role</h3><p style="min-height:1.5em">A Y Combinator-backed consumer wearable AI startup is hiring a <strong>Founding Full-Stack iOS Engineer</strong> to own the company's companion iOS app from the ground up. This is a high-ownership, founding-team role at the intersection of consumer hardware, real-time AI inference, and emotional intelligence. The company is building a first-of-its-kind wearable that reads and interprets a user's emotional state in real time — think a fitness tracker, but for your emotions and cognitive performance.</p><p style="min-height:1.5em">You'll be the primary builder of the consumer-facing mobile experience, translating sophisticated AI model outputs (energy, mood, focus signals derived from audio and biometric data) into intuitive, beautiful interfaces. This role comes with significant equity upside and a clear path to leading mobile engineering as the company scales.</p><p style="min-height:1.5em">The team is distributed, with presence in <strong>San Francisco</strong> and <strong>London</strong>. This role is based in <strong>London</strong>, with flexibility for hybrid or remote working arrangements.</p><h3>What You'll Do</h3><ul style="min-height:1.5em"><li><p style="min-height:1.5em">Own the companion iOS app end-to-end — architecture, development, deployment, and ongoing iteration.</p></li><li><p style="min-height:1.5em">Surface real-time emotional-state outputs from the company's proprietary AI inference model through clean, intuitive app interfaces.</p></li><li><p style="min-height:1.5em">Build and ship a polished, consumer-grade mobile experience that meets high product and design standards.</p></li><li><p style="min-height:1.5em">Integrate backend APIs covering authentication, data sync, and data models.</p></li><li><p style="min-height:1.5em">Make autonomous technical decisions as a founding engineer, setting patterns and standards for the mobile codebase.</p></li><li><p style="min-height:1.5em">Collaborate across time zones with a small, fast-moving distributed team.</p></li></ul><h3>What We're Looking For</h3><p style="min-height:1.5em"><strong>Required:</strong></p><ul style="min-height:1.5em"><li><p style="min-height:1.5em">3+ years of professional iOS development experience with <strong>Swift</strong>, with a proven track record of shipping production-ready, consumer iOS apps.</p></li><li><p style="min-height:1.5em">Demonstrated end-to-end ownership of mobile features — from concept through release and ongoing maintenance.</p></li><li><p style="min-height:1.5em">Strong full-stack capabilities including mobile app development and backend API integration.</p></li><li><p style="min-height:1.5em">Experience integrating machine learning model outputs or inferences into a mobile app UX.</p></li><li><p style="min-height:1.5em">Ability to deliver polished, consumer-grade UI/UX with attention to performance and smoothness.</p></li><li><p style="min-height:1.5em">Comfortable working independently and across time zones as part of a remote/hybrid team.</p></li><li><p style="min-height:1.5em">Work authorization to be employed in the <strong>UK or US</strong> — the company does not offer new visa sponsorship (H-1B transfers considered where applicable).</p></li></ul><p style="min-height:1.5em"><strong>Nice to Have:</strong></p><ul style="min-height:1.5em"><li><p style="min-height:1.5em">Background in data-driven apps that surface complex model outputs through accessible design.</p></li><li><p style="min-height:1.5em">Experience at a consumer hardware, wearable, or health/wellness tech company.</p></li><li><p style="min-height:1.5em">Strong CS fundamentals and comfort owning architectural decisions autonomously.</p></li></ul><h3>Compensation &amp; Benefits</h3><ul style="min-height:1.5em"><li><p style="min-height:1.5em"><strong>Salary:</strong> ~$150,000 USD (US) / ~£75,000 GBP (London) depending on location</p></li><li><p style="min-height:1.5em"><strong>Equity:</strong> Meaningful founding-team equity (up to 1–2%)</p></li><li><p style="min-height:1.5em">Seed-stage company backed by a top-tier accelerator</p></li><li><p style="min-height:1.5em">High-ownership founding role with a clear path to leading the mobile engineering function</p></li></ul><h3>Location</h3><p style="min-height:1.5em">Primary location: <strong>London, United Kingdom</strong>. The team also has a presence in San Francisco, CA. Hybrid and remote flexibility available for the right candidate. <strong>No new visa sponsorship</strong> — candidates must have existing UK or US work authorization (H-1B transfers considered).</p><p>Find more <a href="https://www.arbeitnow.co.uk/english-speaking-jobs">English Speaking Jobs in United Kingdom</a> on Arbeitnow</a>