Swagger, rebranded to Open API, is a specification for documenting and structuring REST APIs that allow for both humans and computers to understand their functionalities. The two main OpenAPI implementations for .NET are Swashbuckle and NSwag. Both of these tools will generate the API json documentation that describes your API.

Swagger UI is a tool that can auto generate a UI website from the documentation that can be used to explore and test your API without connecting through another application.

See Also

• Microsoft Docs - Asp.Net Core Web Api Documentation - https://docs.microsoft.com/en-us/aspnet/core/tutorials/web-api-help-pages-using-swagger?view=aspnetcore-5.0
• Pluralsight Course - Documenting Asp.Net Core with Open Api - https://app.pluralsight.com/library/courses/aspdotnet-core-api-openapi-swagger/table-of-contents