Senior Backend Developer

About the Role Multisynaptech is looking for a Senior C# .NET Backend Developer to join our development team and help build a brand-new web-based platform. This is an unique opportunity to shape the product architecture, influence technology choices, and lay the foundation for a scalable, secure, and high-quality product that simplifies healthcare workflows and improves patient outcomes. If you're a hands-on developer with strong decision-making capabilities and a passion for clean, maintainable systems — let's talk! What You’ll Do Core Responsibilities Design and develop a modern, scalable backend application using C# on .NET Core, serving microservices to a Vue.js frontend. Build secure APIs and integrate databases (SQL and NoSQL). Collaborate on key design and architecture decisions — your input is essential. Ensure the system meets healthcare-grade security, performance, and scalability requirements, aligning with relevant certifications (ISO 27001, NEN 7510). Contribute to CI/CD pipelines and DevOps practices in collaboration with platform engineers. Integration Responsibilities Design and develop robust integrations with external systems such as EHR platforms, payment providers, and other healthcare APIs. Develop data mapping and transformation logic to build integrations that can easily be swapped to prevent vendor lock-in. Work with healthcare standards such as HL7 FHIR, DICOM, or other relevant protocols. Support real-time data streams and ESB-like messaging systems. Who You Are Open and approachable. 5+ years of experience as a backend developer or full stack developer with a strong backend focus. Proven track record of taking ownership of software products and technical architecture from the ground up. Deep knowledge of C# and .NET Core. Experience with cloud platforms (preferably Azure), containerization, and backend engineering in cloud-native environments. Familiarity with ESB concepts and message queueing systems. Strong communication skills and confident expressing yourself in English. Based in the Netherlands, preferably located within 1.5 hours of Rotterdam. Willing to work fully on-site initially. In order to establish the fundamentals, we prioritize on-site collaboration, with flexibility increasing over time. Previous experience in an agile environment. Nice to Have Experience with SaaS platforms. Experience with healthcare integrations (care systems, lab interfaces, etc.). Interest or experience with Go or Rust. Familiarity with authentication protocols such as SAML, OAuth 2.0. Knowledge of security best practices and performance optimization. What We Offer A chance to own the backend architecture and build a new product suite from scratch. Working with a divers and wonderful team. A competitive salary package that reflects your experience and the value you bring to our mission. Extensive growth opportunities. A permanent, full-time position. Interested? We'd love to hear your story! Submit your CV as PDF to info@multisynaptech.org