google recaptcha

index.html

        // 1
        <script src="https://code.jquery.com/jquery-3.4.1.min.js" integrity="sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo="
  crossorigin="anonymous"></script>

        // 2
        <script src="https://www.google.com/recaptcha/api.js?render=reCAPTCHA_site_key"></script>
        <script>
          // 3
          grecaptcha.ready(function() {
              // 4
              $('#contactform').submit(function(e){
                  var form = this;
                  // 5
                  e.preventDefault()
                  grecaptcha.execute('reCAPTCHA_site_key', {action: 'contactform'}).then(function(token) {
                      // 6
                      $('#recaptcha').val(token)
                      // 7
                      form.submit()
                  });
              })

          });
         </script>

settings.py

RECAPTCHA_SITE_KEY = "your site key"
RECAPTCHA_SECRET_KEY = "your secret key"

views_1.py

from django.conf import settings


def index(request):
    """
    simple render index.html
    """

    return render(request, 'index.html', {'site_key': settings.RECAPTCHA_SITE_KEY})

views_contact.py

    secret_key = settings.RECAPTCHA_SECRET_KEY

    # captcha verification
    data = {
        'response': data.get('g-recaptcha-response'),
        'secret': secret_key
    }
    resp = requests.post('https://www.google.com/recaptcha/api/siteverify', data=data)
    result_json = resp.json()

    print(result_json)

    if not result_json.get('success'):
        return render(request, 'contact_sent.html', {'is_robot': True})
    # end captcha verification