Software Engineer, App Developer - Mobile​/Web, AI Engineer (Applied​/Software)

Our mission is to make secondhand the first choice, building the AI‑powered infrastructure for global secondhand commerce. We have already saved millions of items from landfill, are growing rapidly, and are backed by leading VCs after a recent Series B. This role is a Staff Mobile Engineer in London, owning the entire mobile buyer experience for a marketplace that integrates proprietary AI models for item grading and discovery.

• Own the end-to-end mobile buyer experience, building and scaling the core marketplace app (browsing, discovery, purchasing) that directly drives GMV.
• Integrate proprietary AI classification models into the mobile product, translating complex grading and pricing into intuitive, fast, and trustworthy UX.
• Ship new features with craft and velocity, maintaining release stability, reducing crash rates, and optimizing performance across devices.
• Work embedded with Product and Design, shaping product direction by challenging assumptions and bringing technical trade‑offs into early conversations.
• Build and instrument the mobile app for A/B testing and analytics, enabling data‑driven product decisions for the Demand team.

• 4–8 + years of professional software engineering experience, having shipped production mobile apps that handle real users and transactions.
• Deep production expertise with React Native, including comfort navigating the boundary between React Native and native platform code.
• A strong product engineering mindset: you connect UI decisions to conversion outcomes and articulate the business problem your code solves.
• Experience building consumer or marketplace products at scale, with a keen eye for UI craft and performance.
• This role is based in London, requiring 3–4 days in‑office (full‑time for your first six months).