ProjectForum and CourseForum
From 2002-2017, I was working on a wiki software product called ProjectForum, along with an education-specific variant called CourseForum. Unlike something like Wikipedia, these were targeted at smaller groups, providing a place to collaborate with each other. It was easy for people to run their own wiki server (everything was nicely self-contained) on Mac, Windows or Linux, or we also offered a hosted version.