First, we need an API key, so head on over to https://www.google.com/recaptcha/admin. To gain access to this page you’ll need to be logged into a Google account. You’ll be asked to register your website, so give it a suitable name, then list domains (for example ) where this particular reCAPTCHA will be used. Subdomains (such as and ) are automatically taken into account.
With that done you’ll be given a site key and its partner secret key: