- one of the most advanced permissions systems in the whole Fediverse
- private forums that are actually private, protected by the permissions system
- any channel, including forum channels, can hide from directories
- Hubzilla forum channels can be moderated/administered by members anywhere on Hubzilla, (streams) or Forte
- based on the Zot6 protocol; ActivityPub is optional, i.e. you have to activate it for the forum channel manually, and you can "raise the drawbridge" by turning it off again
The only downsides are a somewhat steep learning curve and that Hubzilla can only be used through its Web interface and not through a native phone app.