This article was written by Otavio Santana . Keeping software simple is one of the hardest challenges for any software architect or senior engineer. Not because of technology, but because of decisions we often overlook—especially coupling. Many systems start simple, but as new requirements emerge, the same code begins to orchestrate multiple responsibilities. What once felt clean becomes fragile, and small changes require touching multiple parts of the system. This is how architectures silently degrade. The good news is that there are ways to address this problem. In this tutorial, we will explore an architectural approach that helps reduce coupling and improve extensibility, and how MongoDB can effectively support this style. In this tutorial, you’ll: Model a simple payment system Write events sync and async events Explore how MongoDB can help you on archive Event-driven design.…