Senior Full Stack Engineer (Core Platform & API Squad)

Do you want to build the platform at the core of a health-tech operation that touches hundreds of thousands of lives? Tell us what you need to make it happen. The more successful we are, the more people we help lead healthier, happier lives. About Wellis Wellis is a healthtech scale-up reinventing one of the most traditional sectors there is: healthcare. We started three years ago. Today we serve tens of thousands of customers, and we're only getting started. We combine medical expertise with technology and data to make care accessible, personal, and seamless. People use our platform to take control of their health journey with trusted medical support and tailored programs. We move fast and challenge conventions, because better healthcare should be within everyone's reach. The Role You'll be a core member of the Core Platform & API squad, building the engine behind everything Wellis does. Our API layer is in its early days and needs rethinking and scaling for where the platform is headed, so the work is close to greenfield. You'll shape the data model, the internal API serving our web portal and mobile app, and the business logic behind prescription and medication workflows. The stakes are real. The data is patient medication records, and the people consuming your APIs are pharmacists making clinical decisions. Our stack is TypeScript end to end: React on web, React Native on mobile, Node on the backend. One language and one type system across all of it, so a prescription gets defined once and the compiler enforces it from database to screen. You'll be the backend anchor of that stack. That means bringing real systems discipline: transactions, idempotency, migrations, queues. We're an AI-native engineering team. Agentic coding tools are our primary way of working, and we expect you to work this way from day one. We also expect you to make our agents better. The skills, plugins, and workflows you write should raise the output of everyone around you. What You'll Build The core API layer. What exists today is early-stage, so you get to redesign it properly. Build the internal Node/TypeScript API serving web and mobile: schema-first design, runtime validation at every boundary, auth, pagination, versioning. These are the contracts every other squad will depend on. The data layer. Own the schema covering patient management, clinical data, prescriptions, providers, and devices. Migrations, indexing, query performance, data integrity, across SQL and NoSQL stores as the platform demands. Business logic. Prescription workflows (create, validate, dispense, track), medication record management, patient lifecycle, clinical rules, drug interaction checks. Agentic tooling. Build and maintain the skills, plugins, and agent workflows the team develops with. This is the leverage layer that lets a small team ship like a big one. Integration touchpoints. Data flows with billing, logistics, and ERP systems, plus an external Dutch pharmacy information system. What we offer Salary range € 7.000 - € 10.000 gross per month (depending on experience) Pension plan Learning budget Monthly personal budget (Alleo) Hybrid working: partly from our new office in central Rotterdam (2 days) 20 days of remote working per year Working from home allowance (2 days a week) A culture of short lines, speed, and continuous improvement - where pragmatism and impact matter. The opportunity to help build a fast-growing healthtech scale-up from the inside. Essential 4+ years of professional backend engineering Strong Node/TypeScript is ideal. Deep backend experience in Python, Java, Go, or C# works too, if you can get productive in TypeScript fast. The bar is fundamentals: transactions, idempotency, migrations, queues, API contracts. You write clean, testable, well-documented code. Agentic AI development is how you work. You spend most of your day in tools like Claude Code, Cursor, Pi, or opencode. You've gone past usage and built plugins, skills, or custom workflows that made these tools better for you or your team. End-to-end deployment experience, with the scars to show for it. Schema to API to pipeline to production. Maybe a migration of yours locked a table once, or a deploy took down an endpoint on a Friday. You owned it, fixed it, and built the guardrails so it never happened again. API design experience. You've designed and built APIs that other teams depend on, and you can stand up a well-structured API layer from nothing. Strong database fundamentals. Solid SQL: complex queries, indexing, migrations, performance tuning. Comfortable with NoSQL stores too. Experience with regulated or sensitive data. Healthcare, financial services, legal, or government. You know why 'move fast and break things' has no place near patient data. Nice to have Experience scaling SQL databases (partitioning, replication, connection pooling) and running NoSQL at volume. Python, for integrations, data tooling, and future data or ML services at the edges of the platform. IAM knowledge: auth flows, RBAC, token lifecycles, row-level security concepts. Audit logging in regulated environments (NEN 7513, BDSG, or similar). CI/CD and cloud infrastructure (GCP, AWS, or Azure; Docker). A dedicated DevOps role will own this, but you should be conversant. React and React Native experience. Our web and app squads live here, and full-stack range gets used. Healthcare data standards like HL7 FHIR and MP9. Willingness to learn counts more than prior exposure. Working knowledge of GDPR or equivalent data protection frameworks. Dutch and/or German (business English is the working language). Who You Are You take ownership of what you build, from schema through API through deployment through monitoring. You write code for the next person. Clear naming, documentation, and testability matter to you. You're comfortable in a small team where your decisions carry weight. No hiding behind process. You care about data correctness at a deep level. A wrong medication record can hurt someone. You work fast and stay careful. With Your Application Alongside your CV, share a transcript or a detailed walkthrough of the most interesting agentic coding session you've had in the past few weeks. Pick one where the agent did real engineering work. Tell us what you were building, how you steered the agent, and what you'd do differently. We'd rather read this than a cover letter. Hiring Process We want the application process at Wellis to be fast, transparent, and personal. Introductory chat with Georgios (Senior Recruiter) Introductory interview with Karthik (CTO) Technical assessment with CTO Final conversation with founders If you have questions, please contact