Protege

The industry-standard open-source platform for building intelligent systems and complex ontologies.

Developed by the Stanford Center for Biomedical Informatics Research, Protege provides a robust suite of tools for constructing domain models and knowledge-based applications using the OWL 2 language. It supports a global community of over 300,000 registered users who leverage its flexible architecture to manage structured data in fields like drug discovery, aerospace, and semantic web development. The platform integrates seamlessly with reasoners like HermiT or Pellet to verify logical consistency (ensuring no contradictory relationships exist) and offers a plug-in architecture for custom visualization and data acquisition.

https://protege.stanford.edu