Web Api Documentation with Swagger

 Swagger (or OpenAPI) is a language-agnostic specification documenting your api. You can read more from there, ASP.NET Core web API documentation with Swagger / OpenAPI | Microsoft Docs

Generate a Asp.Net Core web api project with .NET CLI with this command,

dotnet new webapi -o YourApiProject

The template generated with this command already comes with swagger setup. 

First you can verify that by going to YourApiProject.csproj config file, you will see the reference added,

 <PackageReference Include="Swashbuckle.AspNetCore" Version="5.6.3" />

How the swashbucke is setup you can go to this link, Get started with Swashbuckle and ASP.NET Core | Microsoft Docs

Now, go to the Startup.cs file, and in the configure method, you will see how the swagger ui is setup,

    // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),

    // specifying the Swagger JSON endpoint.

    app.UseSwaggerUI(c =>

    {

        c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");

    });

Now when you run your project with dotnet run,  you will see the nice swagger ui in http://localhost:5001/swagger 

To serve the Swagger UI at the app's root (http://localhost:<port>/), set the RoutePrefix property to an empty string:

app.UseSwaggerUI(c =>

{

    c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");

    c.RoutePrefix = string.Empty;

});

Swagger UI will look like this, which allow you to interact with your api.