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.
Vanilla Forums - Build an engaging community forum using Vanilla's modern cloud forum software.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Forumbee - Forumbee offers community forums for discussions, feedback and Q&A.
Slack - A messaging app for teams who see through the Earth!
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.