At Topicus, we are building a new SaaS platform in the Dutch healthcare domain called Healthcare declarations. Our team is responsible for modernizing and migrating legacy applications, originally developed by Topicus, into a scalable, cloud-based, and future-proof platform. It plays a critical role in the Dutch healthcare system, handling the financial processing and payment of healthcare providers. The platform is used to: Validate healthcare claims.Handle complex payment and reimbursement rules.Ensure accuracy, reliability, and timely payouts.Healthcare declarations supports multiple healthcare domains, including:MidwiferyGeneral PractitionersLaboratories (LAB)GP Emergency Services (HAP)Regional GP Organisations (RHO)Given the large volume of financial transactions and strict requirements around accuracy, reliability, and compliance, we are looking for 03 .NET Developers who enjoy working with complex business logic, understand legacy systems, and are motivated to help transform them into a modern SaaS solution. Responsibilities Design, develop, and maintain .NET applications with a strong focus on technical excellence, scalability, and maintainability.Work on modernizing and migrating legacy systems into a cloud-based SaaS architecture.Implement and maintain complex business and financial logic with high accuracy and reliability.Collaborate closely with international team members (mainly in the Netherlands and Vietnam) to deliver high-quality software solutions.Participate in code reviews, ensuring adherence to coding standards and best practices.Troubleshoot, analyze, and resolve technical issues to ensure smooth project execution.Create and maintain clear and comprehensive technical documentation.Support and coach team members when needed, contributing to a high-performing and motivated team.Actively contribute to discussions around technical improvements, architecture, and long-term platform evolution.Technologies & Frameworks Used Languages & Frameworks: .NET C#, .NET Core.Databases: MS SQL Server, PostgreSQL.Architecture & Patterns: Microservices, APIs, CQRS, Event Sourcing, Outbox Pattern.Libraries: WolverineFX, MartenDB.DevOps & CI/CD: Git, Terraform, TeamCity, Octopus Deploy.Cloud: AWS (or similar cloud services).Testing: Unit testing, Integration testing.