Senior Full Stack Engineer (Core Platform & API Squad)

Do you want to build a great platform that is the core of an innovative health-tech operation and will impact the wellbeing hundred of thousands, if not millions of people? Tell us what you need to make it happen! The more successful we are, there more people we will help lead healthier, happier lives! About Wellis Wellis is a fast-growing healthtech scale-up that is reinventing one of the most traditional sectors: healthcare. What started just three years ago has already grown into a company with tens of thousands of customers, and we are only at the beginning. By combining medical expertise with technology and data, we make healthcare smarter, more efficient, and more personal. Our mission is to improve everyday lives by making care accessible, personal, and seamless. Through our platform, people can take control of their health journey with trusted medical support, smart digital tools, and tailored programs. We move fast, challenge conventions, and build solutions that truly make an impact, because we believe better healthcare should be within everyone's reach. The Role You will be a core member of the Core Platform & API squad, working directly on the engine that powers every part of the Wellis platform. You'll build and maintain the PostgreSQL database layer, design and implement FastAPI endpoints, write the business logic for prescription and medication workflows, and contribute to the IAM and signing infrastructure that makes our card-free architecture possible. This is not a role where you build CRUD endpoints and move on. The data you handle is patient medication records. The APIs you build are consumed by pharmacists making clinical decisions. The signing workflows you contribute to have legal force. You need to care about correctness, security, and reliability at a level most backend roles never demand. What You'll Build PostgreSQL / Supabase core: work with a 31-table schema covering patient management, clinical data, prescriptions, healthcare providers, IoT devices, and audit logging. Own migrations, indexing, query performance, and data integrity. FastAPI internal API layer: design and implement the endpoints that serve both the web portal and mobile app. Schema-first API design, request validation, auth token verification, pagination, and response shaping. Business logic: prescription workflows (create, validate, dispense, track), medication record management, patient lifecycle, clinical rules engine, drug interaction checks. Integration touchpoints: work with the Integration/Automation Engineer on data flows between Supabase, Firmhouse (billing), Monta (logistics), and Odoo (ERP/WMS) via the Workato orchestration layer. IAM and security: contribute to Supabase Auth configuration, RBAC policy design, jurisdiction-scoped Row Level Security, and JWT token lifecycle management. Work alongside the IT Systems & Security Manager on Cloud HSM signing workflows. Audit logging: implement tamper-proof audit trails to NEN 7513 (Netherlands) and BDSG (Germany) standards for all data access and clinical operations. CI/CD and infrastructure: contribute to deployment pipelines, GCP infrastructure, monitoring, and alerting. Own the reliability of what you build. 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.