diff --git a/README.md b/README.md
index 0de1cc5..2da3a9c 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,14 @@
 
 Work-in-progress interactive topological router in Rust.
 
-[GitHub mirror](https://github.com/mikwielgus/topola)
+Join the [official Matrix chatroom](https://matrix.to/#/%23topola:tchncs.de) to talk with the
+developers. 
+
+## Contributing
+
+[Official repository on Codeberg](https://codeberg.org/mikolaj/topola)
+
+[Mirror repository on GitHub](https://github.com/mikwielgus/topola)
 
 ## Gallery
 ![Animation. There's a rubber band-like trace following cursor, navigating a very simple maze. The maze and the trace are red, the background is solid black but also very slightly white and dark blue](./assets/interactive_routing.gif)