Senior Full Stack Developer — Product

ABOUT THE ROLE You'll own the product surface end to end: the interfaces where customers design a study, watch a simulated population answer it, and turn thousands of agent responses into a decision they can defend to their board. This isn't CRUD behind an AI feature. A study in Elaiia is a research instrument — question types with real methodological structure (Likert, NPS, rank-order, choice frequency, metric scale, A/B), variant designs where the same twins evaluate different stimuli in isolated sessions, audience comparisons where the independent variable is who answers. It has to be legible to a marketing director who has never run a survey, and precise enough that our research team will stand behind the output. RESPONSIBILITIES – Design and ship production features across the full stack — schema, backend services, API, React surface, migration, tests, flagged rollout – Turn research methods into product, working directly with our behavioural scientists and survey methodologists – Build the analysis and publication layer: charts, effect sizes, verdicts, CSV extracts, PDF reports – Raise the abstraction level as the surface grows — consolidate repeated patterns so each new study type costs less than the last; some of your best work here will be deletion – Ship EN and DE for an international client base – Release incrementally behind feature flags to live enterprise clients YOU MAY BE A FIT IF – 4+ years shipping production TypeScript web applications – Strong React/Next.js expertise with a focus on code quality – Relational schema design at scale — schemas designed, migrations run against live data, and a query debugged that was fine at 100 rows and not at 100,000 – Interest in LLM integration: prompting, structured outputs, RAG, agents – AI tools as standard development practice – Product judgment — you can explain a decision to ship something imperfect, and why it was right – Comfort with ambiguity, and clear technical communication STRONG CANDIDATES MAY ALSO HAVE – Production AI features with real customers – Drizzle or a comparable typed ORM, Hono, durable job engines (Inngest, Temporal) – Internationalised products – Data visualisation or report generation – Early-stage startup experience You don't need a background in AI, market research or behavioural science. Curiosity about all three matters more — several of the most useful things you build here will be explained to you first by someone with a PhD in cognitive science. ABOUT DELTA LABS Delta Labs uses AI to simulate and predict consumer behaviour at scale. We build Elaiia, a simulation engine that generates AI Twins — intelligent synthetic agents that mirror real consumer populations. Our clients use Elaiia to simulate customer decisions before committing to them: pricing strategies, product launches, campaign messaging, channel allocation. We replace surveys, focus groups, and intuition with simulation-based evidence. We're a small, focused team and we intend to stay that way. We give people ownership, trust, and the autonomy to do their best work. We work with urgency and intellectual honesty and expect new team members to match our pace. We seek individuals who are curious, rigorous, and want their work to have demonstrable impact. If you're drawn to the idea of a small team building something that hasn't existed before, let's build together. THE STACK TypeScript frontend (Next.js/React), PostgreSQL, Python microservices, durable background jobs, integrated LLM APIs (OpenAI, Anthropic, Google Gemini), LangGraph agents with tracing. Deployed on Vercel and Microsoft Azure. LOCATION This role is based in Zürich, Switzerland. Delta Labs is an in-person company. Candidates are expected to be located in the Zürich area or open to relocation. BENEFITS Ownership of systems rather than tickets. Direct work with a research team of unusual depth — behavioural scientists, experimental economists, psychometricians and cognitive scientists whose methods you'd be building. A product global enterprises use for decisions that matter. The chance to shape an early-stage company. Delta Labs is an equal opportunity employer, welcoming applicants of all backgrounds.