APIs have seen dramatic growth in the last few years, and they're now powering everything we do. This is causing a fundamental shift in how we write applications - it's not just a UI and a database anymore. This makes good APIs even more important than ever. Come join a fun talk as we explore the best and worst of web APIs. We'll see what makes an API great - and what makes it awful. From data formats to documentation to authentication - there's a lot to learn whether you're building the next Facebook API or you're building a small on-premise application.