Quibble
Quibble is a libre, peer-to-peer chat application: text, files, and voice/video calls with no central server holding your data. It is built on Hyperswarm, Autobase, Corestore, and WebRTC.
How it works
Rooms are multi-writer append-only logs (Autobase) replicated directly between peers - there is no database in the middle.
Identity is an Ed25519 keypair derived from a 24-word seed phrase, so the same identity can move between devices.
Calls connect peers directly over WebRTC, using STUN/TURN only to get the media flowing past firewalls and NAT.