What exactly do you mean with anonymous? Group chats with random, unknown people; or tracking free 1:1?
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.
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.
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.
SimpleX, CWTCH and Jami.
SimpleX Chat and Briar. Also check this link out.
Briar, Session, or self host (e.g. XMPP, OnionShare, IRC, etc.)
