Ever had your API documentation go out of sync with your API implementation? Or broke API clients with a refactor of your back-end code? Or maybe you deployed the wrong version of a microservice to production instead of staging... If the above sends chills down your spine, then this talk is for you! We'll learn how to use open source tooling to test your code against an API spec, during development or in production, so you can ensure your documentation is in sync and that you don't break everyone out there that depends on your API.