Messaging
Matrix / Synapse
Federated, end-to-end encrypted messaging protocol with the Synapse reference server.
Brax recommends
Self-hosted team or community chat when you want E2EE plus federation rather than a walled garden.
Matrix supports E2EE group chat, voice, and video across a federation of servers, similar to email. Synapse is resource-hungry at scale; Dendrite and Conduit are lighter alternatives worth considering.