The Visual Understanding Environment (VUE) is an Open Source project based at Tufts University. The VUE project is focused on creating flexible tools for managing and integrating digital resources in support of teaching, learning and research. VUE provides a flexible visual environment for structuring, presenting, and sharing digital information.
WikkaWiki is a flexible, standards-compliant and lightweight wiki engine written in PHP, which uses MySQL to store pages.
TheBrain is a mind mapping and personal knowledge base software
FreeMind is a premier free mind-mapping software written in Java.
The IHMC CmapTools program empowers users to construct, navigate, share and criticize knowledge models represented as concept maps.
Conzilla2 - our second generation concept browser - is a knowledge management tool with many purposes.