@fiatjaf I said a server but that's basically any machine you have laying around, since with running p2p the cost of scaling network doesn't scale with the number of nodes, the cost of running a node is pretty low. I'm sure if somebody spends a weekend on it we would get a fully running Bitsocial node on Android that hosts a community. You could probably host thousands of communities on a raspberry pi easily. Running communities is free in the economical sense, in the same way seeding a bittorrent file is "free" because there's no DNS to be bought, and u basically have to only leave the app running in the background