Freemind is great for mindmapping in the context of a specific topic or project, but isn't a general purpose knowledgebase. A mindmap starts at a central node

Freemind is great for mindmapping in the context of a specific topic or project, but isn't a general purpose knowledgebase. A mindmap starts at a central node and moves outward. This makes it limited in the practical number of nodes you can have--anything over a couple hundred is hard to manage. It also makes it difficult for one node to appear in multiple places within the mindmap.