From 25 Microservices to 1 (async) Modulith

In this talk, I will share the journey and challenges of migrating Germany's largest coding challenge platform EntwicklerHeld, serving over 45,000 developers, from a microservice architecture to a modulith architecture, while also transitioning to asynchronous processing. I'll dive into key strategies, including database routing, settings merging, and event-driven communication. Additionally, I'll provide an in-depth comparison of performance and cost structures before and after the migration, offering insights and lessons learned along the way.