Users have come to expect real-time collaboration from best-in-class apps like Notion or Figma. But widely available tools and infrastructure for building multiplayer apps are only just emerging. In this talk, we’ll explore the open-source framework Jazz and the two new ideas powering it: Conflict-free Replicated Data Types (CRDTs) and verifiable permissions. By building a whole app with nothing but React and Jazz, we’ll see how this new approach radically simplifies building not only real-time multiplayer apps, but any kind of app in which users interact.