We have added a theory graph viewer to MathHub.

TGView is available at https://mathhub.info/mh/mmt/graphs/tgview.html and can present arbitrary theory graphs whose graph data is generated by MMT.

For instance, the Math-in-the-Middle ontology can be seen as https://mathhub.info/mh/mmt/graphs/tgview.html?type=pgraph&graphdata=htt...

Details can be found in a paper submitted to MathUI 2017.