The proliferation of digital data sources in many domains brings a new urgency to the need for tools which allow to flexibly query heterogeneous data (relational, JSON, key-values, graphs etc.) Traditional data integration systems fall into two classes: data ware-housing, where all data source content is materialized in a single repository, and mediation, where data remains in their original stores and all data can be queried through a mediator. We propose to demonstrate Obi-Wan, a novel mediator following the Ontology-Based Data access (OBDA) paradigm. Obi-Wan integrates data sources of many data models under an interface based on RDF graphs and ontologies (classes, properties, and relations between them). The novelty of Obi-Wan is to combine maximum integration power (GLAV mappings, see below) with the highest query answering power supported by an RDF mediator: RDF queries not only over the data but also over the integration ontologies [6]. This makes it more flexible and powerful than comparable systems.