http://pfpmd7dd5ijt4add2sfi4djsaij4u3ebvnwvyvuj6aeipe2f5llptkid.onion/

This is, perhaps, one of the simplest chat rooms on the deep web. There’s no need to register with it or fill out any forms – just load the website and start typing and sending your messages.

However, you should note that although there are English speakers in this chat room, most of the users seem to be Russian. It allows posting third-party images but you can disable this feature if you want to. It’s not the most effective chat room out there, but it’s seemingly legal in every sense. Also, you can reply to each thread individually.