Protégé

Protégé is an open‑source editor for OWL 2 ontologies, providing tools for modelling, reasoning, querying and managing knowledge structures. It runs as a desktop application on macOS and also offers a browser‑based variant, WebProtégé, that supports collaborative editing. The software is written in Java and uses a plug‑in architecture, allowing users to extend its functionality to suit specific research or workflow requirements.

The platform is used by researchers, organisations and governmental bodies to develop and maintain large‑scale ontologies such as those in the OBO Foundry, the WHO’s ICD‑11 classification, and the NCI Thesaurus. Its support for the full OWL 2 specification enables precise representation of domain knowledge and integration with semantic web technologies.

A community of developers and users contributes documentation, answers questions and creates plug‑ins, keeping the tool maintained and adaptable. The project is released under a free licence and is considered stable for production use.