Matrix / Riot
If you or your workplace uses the professional collaboration system Slack, you might want to consider switching to the open source federated alternative Matrix. Anyone can set up their own Matrix server and use it to collaborate with other people’s Matrix servers.
Matrix includes text chats, audio/video calls, file transfers, bridges to other communication apps and more.
The easiest and most feature-packed app for using Matrix is Riot, which is available for Windows, Mac, Linux, Android and iPhone.
Matrix can also be used directly through the Riot website.
WEBSITE APP – Riot.im
WINDOWS / MAC / LINUX APP – Riot.im
ANDROID APP – Riot.im
iPHONE APP – Riot.im
PROJECT WEBSITE – Matrix.org