I'm curious about the working parameters for someone who comes to peacefo looking for a forum for their community. Is it free to use? If so, for how long? Is it open source? Could I host it on a subdomain? Thanks!

It's free forever for forums with up to 1000 members. Beyond that it is $10/mo to cover server costs. That should be free for most Discord-sized communities. Beyond 10,000 members, a new tier would have to be added. I like how simple peacefo.com is right now for creating a forum. You can link your Forum from anywhere; a website, social media, even on paper. From your forum link, your forum readers aren't captured by peacefo.com at all, except for the footer link. A subdomain function (maybe masking?) could be nice, but could be confusing for account creation. The source is not currently open, though I'm not against doing that. Thanks for asking!