This is how I set up my own Matrix server on a Raspberry Pi with Docker. Unfortunately, the Matrix community has stopped releasing ARM images, so the latest version that will work on ARM is v1.26.0. These instructions will work the same for x86_64 systems, except you’ll be able to use the default x86_64 images in the docker-compose file. This installation comes with Maubot and matrix-registration containers too. If you don’t want to use those features, leave out those sections of the docker-compose config and don’t follow the instructions in the corresponding sections.

Matrix is a federated, open source chat system. By federated, we mean that people can communicate across different servers, like in the image below. In that way, it works sort of like email: even though you may use you@gmail.com and I might use me@kylrth.com, we can still write each other emails. In our case, I host the server at matrix.kylrth.com, and you and I can connect to it with various clients.