This paper describes the OWL ontology explorer OntoXpl. It is available as a web server based on the tomcat architecture. Standard HTML browsers can be used to interact with OntoXpl. At least three potential user groups are targeted by OntoXpl's design: (i) users with a limited background of ontologies and OWL; (ii) ontology developers that are OWL experts; (iii) users interested in understanding and reusing existing ontologies. OntoXpl is intended to complement existing ontology editors and does not offer any editing support. The current implementation of OntoXpl is based on the OWL DL reasoner Racer and uses Racer's extensive query interface in order to support the exploration of OWL ontologies.