Senior Full Stack Developer

About the role

Delta Labs builds Elaiia, a simulation engine that creates AI Twins to predict consumer behaviour at scale, so clients can test pricing, product launches, campaigns and channel allocation before acting. As a Full Stack Developer you will design and build the systems powering Elaiia, from database schema to production UI, keeping it fast, reliable and scalable. The role is based in Switzerland, with work from Zürich and regular in-person meetings; candidates should be based in Switzerland or open to relocation.

Key responsibilities

• Design and build production features across the full stack, from data model to UI
• Integrate LLM APIs into production workflows: prompt pipelines, structured outputs, token optimisation and reliability at scale
• Build and operate long-running, multi-step simulation workflows that run for minutes or hours and cannot silently fail
• Treat LLM quality as measurable: tracing, evals and regression checks on the AI paths you own
• Own entire features end-to-end and take responsibility for their performance, quality and correctness
• Collaborate with the research team to turn experimental AI capabilities into production-grade systems
• Improve and extend the platform architecture as simulation workloads grow, and ship continuously

Required profile

• 4+ years of experience shipping production web applications in TypeScript
• Strong in the modern React/Next.js ecosystem, with attention to code quality, performance and maintainability
• Comfortable reading and writing Python, or ready to become one
• Designed relational database schemas that hold up under real-world scale and complexity
• Experience with or curiosity about LLM integration: prompt engineering, structured outputs, RAG, agent architectures
• Uses AI tools as a core part of the development workflow
• Comfortable with ambiguity and incomplete specifications, clear communication and documentation
• Strong candidates may also have built AI features used by real customers, long-running async job pipelines, multi-tenant systems with enterprise SSO, and experience on both Vercel and Azure

Required skills

• TypeScript and modern React/Next.js
• PostgreSQL
• Python
• Vercel and Microsoft Azure
• LLM integration and LangGraph agents

What we offer

• A competitive salary and potential equity participation
• The chance to build a company from its earliest stages