We propose a Web-based application for revising an OWL ontology. The main functionality of this application consists in changing as less as possible an initial ontology when adding a new piece of knowledge such as an axiom, an assertion. To be able to ensure such a minimal change in preserving con- sistency of the resulting ontology, we use a set of models generated by a tableau algorithm to characterize the semantics of an ontology, and define a semantic distance between ontologies. Our Web-based application provides also other services such as visualizing an OWL ontology in a succinct syntax, inputting an OWL axiom/assertion.