SimpleX Chat and Briar. Also check this link out.
What exactly do you mean with anonymous? Group chats with random, unknown people; or tracking free 1:1?
SimpleX might be worth a look. Although, I think the developer eventually wants to pursue a two-tiered business model. Otherwise, for something like Matrix (where there are several client apps available), no-one’s forcing you to give over your actual details.
Briar, Session, or self host (e.g. XMPP, OnionShare, IRC, etc.)
Session
What you want to do exactly cos i know an app called Session but idk exactly what you mean with “Anonymous”, if you want some kind of app like WhatsApp but for securely communication I suggest you that app.
You can probabaly use element.io or some other matrix chat apps. Those are pretty “anonymus” if you want it to be. Or you can use signal.
