RDF Gravity was developed by Salzburg Research, Knowledge Information Systems Group, Austria. The main purpose of the tool is to provide visualization of RDF/OWL graphs and ontologies. The software is available free of charge under the license of Salzburg Research Forschungsgesellschaft mbH.

RDF Gravity was developed by using the JUNG Graph API and Jena semantic web toolkit. In addition to the resilient graph user interface there is a big variety of functions for customizable graph views. Graph filtering seemed to me one of the most notable features as it allows a lot of flexibility in working with data visualization. Local and Global filter panels make visualization easily manageable. For instance Global Filters can give more generic view of the data. By selecting “subClassOf” one can see that the detailed edge relations visible before were automatically hidden. It’s possible to manipulate the graph in a reverse manner to focus on more specific description of edges and concepts. The availability of such filters makes data visualization very flexible to work with. In addition to applying different filters there is another helpful feature – a good selection of nodes to be displayed. 

Despite user–friendliness of RDF Gravity there are some pitfalls in running the program. The program can be opened with 'Java Web Start' and seems to load everything but then won't launch the app due to some unsigned entry issue.   

The website is closed and the webstie below is the capture of RDF Gravity from wayback machine

http://semweb.salzburgresearch.at/apps/rdf-gravity/

RDF Gravity was used in this research abstract available in XML format https://raw.githubusercontent.com/lehkost/ToolXtractor/master/data/xml/2015/SIMPSON_John_Edward_Building_Better_Linked_Data___Ontol.xml