Haumbaus

Small private XMPP and Matrix Server

XMPP

XMPP is a well established messaging protocol which can federate. This server has federation turned on, so you can contact anyone on this server with their ID(<username>@haumbaus.eu), even when you are using another server.

Clients

Conversations - Android
Dino - Linux and MacOS
Gajim - Linux, MacOS and Windows

More clients listed here.

Public Server

Jabber.de
Magic Broccoli
Anoxinon

Matrix

Matrix is a newer messaging protocol which also can federate. This server has federation turned on, so you can contact anyone on this server with their ID(@<username>:haumbaus.eu), even when you are using another server.

Clients

Fluffychat - Linux, MacOS, Windows, Android and iOS
Nheko - Linux, MacOS and Windows

Public Server

Nitrochat
Tchncs
matrix.im