Standard JWT Authentication Configuration

appsettings.json

{
  "Auth":{
    "JwtSecret":"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}

CreateTokenEndpoint.cs

public class CreateToken : EndpointWithoutRequest
{
    public override void Configure()
    {
        Get("token");
        AllowAnonymous();
    }

    public override async Task HandleAsync(CancellationToken ct)
    {
        var jwtSecret = Config["Auth:JwtSecret"]!;
        await SendAsync(JWTBearer.CreateToken(jwtSecret, p => p["UserId"] = "001"));
    }
}

Program.cs

var bld = WebApplication.CreateBuilder(args);
bld.Services
   .AddAuthentication(
       o =>
       {
           o.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
           o.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
       })
   .AddJwtBearer(
       o =>
       {
           o.TokenValidationParameters = new()
           {
               ValidateAudience = false,
               ValidateIssuer = false,
               ValidateLifetime = true,
               ValidateIssuerSigningKey = true,
               IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(bld.Configuration["Auth:JwtSecret"]!))
           };
       });
bld.Services
   .AddAuthorization()
   .AddFastEndpoints()
   .SwaggerDocument();

var app = bld.Build();
app.UseAuthentication()
   .UseAuthorization()
   .UseFastEndpoints()
   .UseSwaggerGen();
app.Run();

ProtectedEndpoint.cs

sealed class Protected : EndpointWithoutRequest
{
    public override void Configure()
    {
        Get("protected");
        Claims("UserId");
    }

    public override async Task HandleAsync(CancellationToken c)
    {
        var userId = User.FindFirstValue("UserId");
        await SendAsync($"You are [{userId}] and is authorized!");
    }
}