Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
TidyHQ - Organization management tool to support membership, subscriptions, event planning, and outreach.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Slack - A messaging app for teams who see through the Earth!