Sometimes consumers of your APIs require near-realtime communication because regular RESTful HTTP apis can be a few milliseconds too slow. These performant and scalable APIs can be made over websocket TCP connections where events are pushed from client and server in near-realtime fashion. This talk is a story of how I built such an API. We'll look at why this decision to create a websocket API was made and we will take a look at the data that supported this decision. We will take a deep dive into Phoenix websockets, channels, and transports to expose the underlying architecture. Finally, we look at how we tested the API, how we authenticated users over the channels, and how Phoenix helped this all happen with relative ease. Check out our new channel: NDC Clips: @ndcclips Check out more of our featured speakers and talks at https://ndcconferences.com/ https://ndcoslo.com/