HYDRA is a SPARQL engine for querying SADI Semantic Web services, based on a scalable proprietary architecture, algorithms and data structures. It also implements simple federated querying of multiple SPARQL endpoints. It comes with an intelligent browser-based GUI for query composition intended for non-technical users.

HYDRA can be used to query multiple distributed sources of data as a single database. Moreover, the data sources may be completely heterogeneous and include regular relational DB, online DBs, nomenclatures, ontologies, unstructured data such as scientific publication, Web services and various analytical programs. Practically any data that can be processed programmatically may be integrated with other resources. This unprecedented power of integration is achieved by wrapping the data sources as SADI Semantic Web services and orchestrating them in the engine to answer SPARQL queries.