Create a key
Create a CAPTCHA key in the dashboard and add every allowed website origin, including scheme and port where needed. The site key is public and belongs in the widget; the secret key stays on your server and must not be placed in browser code.
Verify on the server
Render the widget in your form and send its resulting token with the form submission. Your server must verify the token using the CAPTCHA verification API and its secret before accepting the action. Treat a failed, expired or already used token as a failure and request a fresh challenge.
Troubleshoot
Check the exact origin and key pair, ensure the server can reach the verification endpoint, and inspect the returned error without logging secrets or tokens. Use the CAPTCHA integration guide for the current widget and verification examples.