Bind mode

Hook the widget to an existing submit button. No extra DOM, no UI rewrite — the click triggers verification, and your form submits after success. View source.

Live demo

Click the existing submit button — the widget intercepts, verifies, then your handler fires.

View HTML source SDK loader source Backend verify.php

Integration code

<script src="https://cdn.captcha-cdn.net/captchala.js"></script>

<!-- Your existing form, untouched -->
<form action="/login" method="POST">
  <input name="email" required>
  <input name="password" type="password" required>
  <input name="captcha_token" type="hidden">
  <button id="login-btn" type="submit">Sign in</button>
</form>

<script>
Captchala.init({
  appKey: 'YOUR_APP_KEY',
  product: 'bind',
  bindTo: '#login-btn',
  action: 'login',
  onSuccess: (res) => {
    // Insert token, submit form programmatically.
    document.querySelector('[name=captcha_token]').value = res.token;
    document.querySelector('#login-btn').form.submit();
  }
});
</script>

When to use bind

Adding verification to an existing form without redesigning the UI. The widget hooks the button click, completes verification, then submits the form normally — your existing backend handler doesn't change at all (it just sees a new captcha_token field).