The capability of the Web in handling text and multimedia information is well known but diagram handling on the Web remains an insufficiently explored field. The motivation for this research was the Cytokine WebFacts project, a database of information about Cytokines to be created and updated by cytokine experts. The data to be stored on the Cytokine WebFacts included text, images and cytokine signal pathway diagrams. The pathway diagram database, the most challenging part, was formed of diagrams submitted by users. Having established the diagram database, functions were developed to allow users to index and search diagrams, embed links within them, publish alternative views of diagrams, modify other people’s work and so on. To enable these functions, a new set of tools were developed and are described here. Very little of this work is domain specific and thus could be of use in other application domains.