simple invisible recaptcha example, works with multiple forms

index.html

<script src='https://www.google.com/recaptcha/api.js?hl=de'></script>

check https://developers.google.com/recaptcha/docs/invisible

<div
    id="header_recaptcha"
    class="g-recaptcha"
    data-sitekey="6LctdiQUAAAAAOTUOX92-PkGJXpZgGUp5hrq4l65"
    data-size="invisible"
    data-callback="recaptcha_submit"
    ></div>
<input type="hidden" name="recaptcha" value="">

somewhere-in-js.js

var on_code_form_submit = function(e) {
    var response = grecaptcha.getResponse();
    if (!response) {
	e.preventDefault();
	$(this).attr('data-submit-please', 'true');
	grecaptcha.execute();
    } else {
	$(this).find('input[name="recaptcha"]').val(response);
    }
};

function recaptcha_submit(token) {
    var $form = $('form[data-submit-please="true"]');
    $form.find('input[name="recaptcha"]').val(token)
    $form.submit();
}

utils.py

def is_valid_recaptcha(request, token_response):
    ip = get_client_ip(request)
    secret = settings.RECAPTCHA_SECRET
    data = {
        'secret': secret,
        'response': token_response,
        'remoteip': ip,
    }
    url = 'https://www.google.com/recaptcha/api/siteverify'
    http_response = requests.post(url, data)
    json = http_response.json()
    if json['success'] == True:
        return True
    return False

you might not want to show your key