Plugins for NodeBB: Invitation code for registered users
Admins can generate invitation codes, which could be broadcasted or given to early users. The forum is open for all to register, but with basic privilege only. Those who has invitation codes could post their codes in profile page, and thus be added to a group(invited) with higher privilege. Access Control Logic should be set for the group invited and uninvited to make it work as you wish.
Installation
npm install nodebb-plugin-invitation-code