Program.cs

using System.IO;
using DNTCaptcha.Core;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

var builder = WebApplication.CreateBuilder(args);
ConfigureLogging(builder.Logging, builder.Environment, builder.Configuration);
ConfigureServices(builder.Services, builder.Environment);
var webApp = builder.Build();
ConfigureMiddlewares(webApp, webApp.Environment);
ConfigureEndpoints(webApp);
webApp.Run();

void ConfigureServices(IServiceCollection services, IWebHostEnvironment env)
{
    services.AddDNTCaptcha(options =>
    {
        // options.UseSessionStorageProvider(); // -> It doesn't rely on the server or client's times. Also it's the safest one.
        // options.UseMemoryCacheStorageProvider(); // -> It relies on the server's times. It's safer than the CookieStorageProvider.
        options
            .UseCookieStorageProvider(
 /* If you are using CORS, set it to `None` */) // -> It relies on the server and client's times. It's ideal for scalability, because it doesn't save anything in the server's memory.
            // options.UseDistributedCacheStorageProvider(); // --> It's ideal for scalability using `services.AddStackExchangeRedisCache()` for instance.
            // options.UseDistributedSerializationProvider();

            // Don't set this line (remove it) to use the installed system's fonts (FontName = "Tahoma").
            // Or if you want to use a custom font, make sure that font is present in the wwwroot/fonts folder and also use a good and complete font!
            .UseCustomFont(Path.Combine(env.WebRootPath, "fonts", "tahoma.ttf")).AbsoluteExpiration(7)
            .RateLimiterPermitLimit(
                10) // for .NET 7x, Also you need to call app.UseRateLimiter() after calling app.UseRouting().
            .ShowExceptionsInResponse(env.IsDevelopment()).ShowThousandsSeparators(false)
            .WithNoise(0.015f, 0.015f, 1, 0.0f).WithEncryptionKey("This is my secure key!")
            .WithNonceKey("NETESCAPADES_NONCE")

            //.WithCaptchaImageControllerRouteTemplate("my-custom-captcha/[action]")
            .InputNames( // This is optional. Change it if you don't like the default names.
                new DNTCaptchaComponent
                {
                    CaptchaHiddenInputName = "DNT_CaptchaText",
                    CaptchaHiddenTokenName = "DNT_CaptchaToken",
                    CaptchaInputName = "DNT_CaptchaInputText"
                }).Identifier("dnt_Captcha"); // This is optional. Change it if you don't like its default name.
    });

    services.AddControllers(); // this is necessary for the captcha's image provider
    services.AddRazorPages();
}

void ConfigureLogging(ILoggingBuilder logging, IHostEnvironment env, IConfiguration configuration)
{
    logging.ClearProviders();

    logging.AddDebug();

    if (env.IsDevelopment())
    {
        logging.AddConsole();
    }

    logging.AddConfiguration(configuration.GetSection("Logging"));
}

void ConfigureMiddlewares(IApplicationBuilder app, IHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler("/Error");

        // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
        app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();

    app.UseRouting();
    app.UseRateLimiter();

    app.UseAuthorization();
}

void ConfigureEndpoints(IApplicationBuilder app)
    => app.UseEndpoints(endpoints =>
    {
        endpoints.MapRazorPages();

        // this is necessary for the captcha's image provider
        endpoints.MapControllerRoute("default", "{controller=Home}/{action=Index}/{id?}");
    });