To start using reCAPTCHA, you need to sign up for an API key pair for your site. The key pair consists of a site key and secret key. The site key is used to invoke reCAPTCHA service on your site or mobile application. The secret key authorizes communication between your application backend and the reCAPTCHA server to verify the user's response. The secret key needs to be kept safe for security purposes.
First, choose the type of reCAPTCHA and then fill in authorized domains or package names. After you accept our terms of service, you can click Register button to get new API key pair.