PQViz (Protégé Query and Visualization tool) provides a search interface for Protégé ontologies. The results are displayed visually as a graph. The results can be explored interactively by manipulating the graph and the graph can be filtered based on concept and relationship types.

A joint product of the NCBO and the CHISEL Group, PQViz came out of the development of CogZ. PQViz uses the neighborhood visualization aspect of CogZ, allowing users to compare the structural relationships of two concepts when querying Protégé ontologies. If you are interested in trying it out, first download Protégé if you do not already have it. Then download PQViz here.