Games Like Ontonaut

Ontonaut is a workbench for OWL 2 ontologies and SKOS vocabularies. It reads and writes plain text files that live in your git repository, and it keeps the logic readable in plain English alongside the syntax. If you have used Protégé, think of Ontonaut as the modern take on the same job.

One file, five views

Your ontology stays a plain Turtle file. Ontonaut also opens RDF/XML and JSON-LD, and saves to all four formats.

Readable by design

Every axiom carries its plain English reading next to the logic, so a subclass statement also reads as "Every Woman is also a Person". Reviews go faster, and the domain experts on your team can follow the model without knowing Manchester syntax. When a spec question comes up, the built-in reference pages settle it with the W3C primers' own examples. SKOS integrity rules are checked as you type, so a vocabulary that leaves Ontonaut follows the spec.

Built for AI collaboration

Ontonaut is an MCP server. Connect any MCP client and it can search, query and edit the ontology you have open, live. Every triple an agent writes is stamped with a provenance annotation and wears an AI badge in the interface. Agent edits sit in your undo history like your own.

Honest about the details

The built-in reasoner is structural. It finds unsatisfiable classes, inconsistencies and inferred hierarchies fast, but it is not a complete DL reasoner, so keep HermiT or ELK in your pipeline for full checking. Saving defaults to Turtle because clean diffs matter. Everything runs locally and your files never leave your machine.