API Visualization with Scalar

Program.cs

using FastEndpoints.Swagger;
using Scalar.AspNetCore; //dotnet add package Scalar.AspNetCore

var bld = WebApplication.CreateBuilder(args);
bld.Services
   .AddFastEndpoints()
   .SwaggerDocument(); //define a swagger doc - v1 by default

var app = bld.Build();
app.UseFastEndpoints(); //must come before the UseOpenApi() call

if (app.Environment.IsDevelopment())
{
    //scalar by default looks for the swagger json file here: 
    app.UseOpenApi(c => c.Path = "/openapi/{documentName}.json");    
    app.MapScalarApiReference();
}

app.Run();

//scalar ui can be accessed at: http://localhost:{port}/scalar/v1

Thanks, @dj-nitehawk! I think it's a good time to upgrade the FastEndpoints documentation and mention Scalar UI.

I create another alternative. Example

don't think that's gonna work: FastEndpoints/FastEndpoints#906 (comment)

So I have discovered that if you want the document name to be different, you must specify the document name in the MapScalarApiReference options. This is seemingly because Scalar defaults to "v1". Please let me know if there is a smoother way to do this.

Example:

const string openApiDocName = "my-api-v1";

app.UseOpenApi(options =>
{
  options.Path = "/openapi/{documentName}.json";
});
app.MapScalarApiReference(
  "/api-reference",
  options => options
             .WithTheme(ScalarTheme.Kepler)
             .AddDocument("v1", "My API v1", $"/openapi/{openApiDocName}.json"));