To organize collectively, we use a bunch of open source IT tools.

Internal tools:

To communicate, we sometimes have online calls, we have a general chat where we discuss daily informal organization may happen, we also have an internal mailing list where we diffuse key decisions or internal updates.
We also have a public cloud to share interesting contents, decisions minutes... and we have a database to share knowledge we acquired (that can go from "how to make good compost" to cooking recipes or any skill we want to share and feel can be useful to others).

External tools:

For the broader community (those interested in simply following us for the moment), we have a general mailing list, where we post only important updates (low email frequency) to keep people up to date on how our community building is evolving.
We also have this website at magari.eauchat.org and our email address magari[(at)]eauchat.org for any questions