Modern software architectures are amidst a paradigm shift — more and more software landscapes are built upon event-driven and reactive patterns. This movement is understandable, as it takes scalability, resilience, and real-time integration to an elusive new level. Unfortunately, we observe that many new customer projects only use parts of this paradigm shift sensibly. Thus, they often introduce a lot of accidental complexity without utilizing the full potential of reactivity. We will start by unpacking the core theories and ideas behind the reactive manifesto. This foundation will allow us to build reactive systems upon event streams and different asynchronous integration patterns. We will further introduce the concept of hydrations, projections, and event stores which uncovers the full potential of FaaS and a cloud-native architectural style that treats elasticity and resilience as first-class citizens. Upon a closer look at the challenges we’ve experienced in customer projects, it turns out that such reactive architectures can be a perfect fit, but are not a silver bullet either. Instead, they are suited for a specific set of problems. In a nutshell, reactive architectures can be a game-changing tool to build cloud-native applications. This talk will give you the needed knowledge to make the choice.