Clicky does not have a feature that blocks visitors from accessing your site. There's no reliable way for us to do this anyways, since the visitor could just block our code from running.

You can use the info you find on Clicky however, such as an IP address or UID, to accomplish this goal.

This image shows where you can find the IP and UID values in a visitor session. Below the image are instructions for Cloudflare, Apache, and Nginx.