samples/BlazorWebAssemblySample/Client/Program.cs

using System.Security.Claims;
using BlazorWebAssemblySample.Client;
using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Authentication;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;

var builder = WebAssemblyHostBuilder.CreateDefault(args);
builder.RootComponents.Add<App>("#app");
builder.RootComponents.Add<HeadOutlet>("head::after");

builder.Services.AddHttpClient("BlazorWebAssemblySample.ServerAPI", client =>
{
    client.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress);
})
    .AddHttpMessageHandler<BaseAddressAuthorizationMessageHandler>();

// Supply HttpClient instances that include access tokens when making requests to the server project
builder.Services.AddScoped(sp => sp.GetRequiredService<IHttpClientFactory>().CreateClient("BlazorWebAssemblySample.ServerAPI"));

builder.Services.AddApiAuthorization(x =>
{
    x.UserOptions.NameClaim = ClaimTypes.Name;
});

await builder.Build().RunAsync();