Первая программа на ASP.NET Core — Минимальный API (без контроллеров)

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.MapGet("/health", () => Results.Ok(new { status = "ok" }));

app.MapGet("/hello/{name}", (string name) =>
    Results.Ok(new { message = $"Hello, {name}!" }));

app.Run();