For my old chatroom, I was using a Java applet chatroom that had no real authentication, called Morevil Chat, the unregistered version. You have to pay for it, and it really isn’t that good, compared to the open-source one I have found. Now I’m using Ajax Chat that utilizes javascript, PHP, MySQL and XML to trasmit and receive messages. I’m very very impressed. The response time is phenomenal and you can setup registered users as well as allow anyone in as a guest with a username of their choice. Anyway, check it out! https://www.westerfunk.net/chat/

Also, here is the site I obtained AJAX Chat from: https://blueimp.net/ajax/