Matrix Synapse Matrix is a Federated IM, VoIP and Video server. In Matrix, every user runs one or more Matrix clients, which connect through to a Matrix homeserver. The homeserver stores all their personal chat history and user account information, much as a mail client connects through to an IMAP/SMTP server. Enable this if you are running a Matrix Synapse homeserver to create local Matrix accounts that can federate with accounts on other servers.