This paper proposes a demo of the TopX search engine, an extensive framework for unified indexing, querying, and ranking of large collections of unstructured, semistructured, and structured data. TopX integrates efficient algorithms for top-k-style ranked retrieval with powerful scoring models for text and XML documents, as well as dynamic and selftuning query expansion based on background ontologies. Categories and Subject Descriptors: H.2.4 [Systems]: Textual Databases, H.3 [Information Storage and Retrieval]: General General Terms: Performance