Matrix
Matrix defines a set of open APIs for decentralised communication, suitable for securely publishing, persisting and subscribing to data over a global open federation of servers with no single point of control. Uses include Instant Messaging (IM), Voice over IP (VoIP) signalling, Internet of Things (IoT) communication, and bridging together existing communication silos - providing the basis of a new open real-time communication ecosystem.
Clients
Desktop clients
A few Matrix desktop clients are packaged for NixOS.
A Pidgin / libpurple plugin is also available.
Web clients
There is also a web version of Riot which can be served using a web server. See the NixOS manual entry.
Servers
Homeservers
Synapse
Currently, only the reference Matrix homeserver Synapse is packaged for NixOS. It has an associated module exposing the services.matrix-synapse.* options. See the NixOS manual entry for a complete configuration example.
Application services (a.k.a. bridges)
mautrix-telegram
Packaged as mautrix-telegram. Module still a WIP.
mautrix-whatsapp
Packaged as mautrix-whatsapp. Module still a WIP.
matrix-appservice-irc
Package and module still a WIP.
matrix-appservice-discord
Package and module still a WIP.