reCaptcha

https://www.google.com/recaptcha/admin/create

v2 or v3

Choose whether you want to use v2 or v3.
• You will be given the following two keys:
• Site Key (for the client side)
• Secret Key (for the server side)

Kopyala

                        public class HomeController : Controller
{
    private const string SecretKey = "YOUR_SECRET_KEY";

    [HttpPost]
    public async Task<IActionResult> Submit(string name, string email, string message, string g_recaptcha_response)
    {
        var httpClient = new HttpClient();
        var response = await httpClient.PostAsync(
            $"https://www.google.com/recaptcha/api/siteverify?secret={SecretKey}&response={g_recaptcha_response}",
            null);

        var jsonString = await response.Content.ReadAsStringAsync();
        dynamic result = JsonConvert.DeserializeObject(jsonString);

        if (result.success == "true")
        {
         
            return Content("Form success!");
        }
        else
        {
            return Content("Please perform reCAPTCHA verification.");
        }
    }
}
                    

Design

Kopyala

                        <form action="/Home/Submit" method="post">
    <input type="text" name="name" placeholder="Name" required />
    <div class="g-recaptcha" data-sitekey="YOUR_SITE_KEY"></div>
    <button type="submit">Gönder</button>
</form>

<script src="https://www.google.com/recaptcha/api.js" async defer></script>