From Legacy to Longevity – How a 17-Year-Old System stayed Modern

Our core claims system in the health insurance domain has been running reliably for 17 years. Originally built from scratch as a monolithic java application, it still forms the backbone of our business operations today. Rather than replacing it through a rewrite, we chose a different approach: continuous modernization. Step by step, we migrated the system to the cloud, improved scalability, introduced modular structures, and continuously updated it to the latest Java and Spring versions – all while keeping the system fully operational. Throughout this journey, we often had to prove that our system could stand up against commercial solutions. Each modernization step was not only a technical improvement but also a statement that a well-maintained, custom-built system can remain competitive, flexible, and cost-efficient if continuously evolved. It required alignment and understanding across all stakeholders – from developers and architects to our users and management. Everyone had to embrace the idea that modernization is an ongoing evolution rather than a single project. In this talk, I will share authentic insights into the realities of modernizing a large, business-critical system while it continues to serve millions of claims inquiries annually. I will also reflect on key challenges we faced and the lessons we learned on the way to achieve a future-proof claims system.