Quassel works like that - you've got a core, and few clients - the default, Qt-based one, Android one, web-based one, even an Irssi plugin to connect to it. Th

Quassel works like that - you've got a core, and few clients - the default, Qt-based one, Android one, web-based one, even an Irssi plugin to connect to it. There's also The Lounge, which looks pretty nice, but I haven't tried: https://thelounge.chat/ https://thelounge.chat/