OpenAPI is the standard way to describe your HTTP API, adopted by most modern APIs. With the spec at the centre of your workflow, you can improve the quality of your API and development practices, and make integrations painless. With standardisation comes tooling and in this session, I will show you to leverage this to your advantage. We'll cover what OpenAPI is, why it's interesting and then how to use it. We will also look at how the OpenAPI specification enables you to create documentation, use mock servers and improve the robustness of our API with validation. This session is ideal for anyone who wants to write an API specification once and use it everywhere.