In this tutorial, we are going to cover how to add NSwag to Asp Net Core 3.0 web API using Visual Studio 2019 preview. NSwag is a Swagger/OpenAPI 2.0 and 3.0 API toolchain for .NET Core, .NET, Web API, TypeScript, Angular, and other platforms which is written in c#. The swagger specification uses JSON and JSON schema to describe a RESTful web API. The NSwag project provides tools to generate swagger specifications from existing Asp.Net web API controllers and client code from these swagger specifications.