This paper reports on a collaborative product development and knowledge management platform for small to medium enterprises. It has been recognised that current product lifecycle management (PLM) implementations are document oriented, have a non-customisable data model and inter-enterprise integration difficulties. To overcome these, an ontological knowledge management methodology utilising the semantic web initiative data formats was added to a PLM and an open source alternative. Shortcomings of centralised architectures are highlighted and a solution using a de-centralised architecture proposed. This is implementable at low cost; the scalability increases in line with user numbers. Ontologies, rules and workflows are reusable and extendable.