Vampires do self-host. They

• use liquid temperature regulation
• transmit P2P to flash images on new devices
• have a future-proof frontend
• use cloud backup
• unless you caught one by surprise, their only real surface of attack requires physical access to the backend

I hear about people wanting alternatives to discord though I never got into using it too much personally, but does anyone know about whether or not Revolt chat is a good open-source self-hostable solution?