.NET 9 makes some impactful changes for creating .NET applications with OpenAPI support! In this session, we’ll dive into the breaking changes and latest OpenAPI advancements for .NET 9 and explore how these features can be leveraged to create robust, efficient, and well-documented APIs. We will cover both minimal API's and controllers.

Afterwards, we'll also talk about Kiota, a new API client generator from Microsoft, and how it can be used to generate API clients based on an OpenAPI document.

This presentation will feature lots of demos with the aim of giving you an end-to-end experience of the latest and greatest features of OpenAPI in .NET 9 and how this can be used with OpenAPI tooling to generate and use API clients!