Matrix is an open protocol for instant messaging. That means that anyone can run or write a client or a server that works with Matrix. It offers end-to-end encryption and federation, so your server can speak to anyone else's.

The API spec is available, and you can do absolutely anything that the clients can.

You can extend the specification, because the events are just JSON objects. If your client can interpret the events, then your custom events will display.

Chat Hackers uses the Whatsapp Bridge that runs on our Matrix server.

Spacetube, my tool that connects different platforms together runs through Matrix because of all the different bridges and interoperability tools.

Chris Owen, a member of the 2025 cohort made Polymorph, a chat client that changes its user interface for each room to match the content.

I made the Virtual Bath to demonstrate that it can be used as a source of events.

And you don't even have to use it for chat, I used Matrix as an easy back-end for data storage for the Anti-University Festival site from 2025.

Matrix is my first choice for interacting with chat.