"Knowledge Tree is an open source document management system
(DMS) that helps enterprise users categorize, store, index, and
share documents. It offers features like metadata editing,
versioning, and WebDAV access, which make it a better choice than a
simple file server for sharing documents.
"The open source edition of the PHP-based Knowledge Tree ships
under GPLv3; a commercial version with some additional features and
support bundled is also available..."