Phylosopher is built on scalable, industry-standard relational Oracle® database technology for storing and interconnecting biomolecules, annotation, sequences, pathways, regulatory elements and expression profiles. A flexible Web interface offers powerful query capabilities, as well as interactive visualizers and tools to drill down into the data. Data content is managed through a rich toolkit, and public APIs enable integration into existing research IT environments. The unique ‘Xtend’ API lets you build custom extensions and query forms to integrate external databases and sources into the user interface with minimal effort.