KBpedia Knowledge Graph
Integrates 7 knowledge bases (Wikipedia, Wikidata, Schema.org, DBpedia, GeoNames, OpenCyc, UNSPSC) into 58K+ concepts.
Visit WebsiteBrowse the tree, filter it, or click any class to see just its corner of it.
Where this one tends to earn its keep.
Knowledge-based AI applications
Cross-vocabulary entity classification
Semantic search enhancement
Data interoperability layer
I haven't checked this label against the actual licence text — it's the catalogue's original guess. Check the ontology's own site before you rely on it.
Others worth a look in Knowledge Graphs.