Wikibase

Wikibase is the back-end database behind the Wikidata project, run by the Wikimedia Foundation which also runs Wikipedia. It is an extension of the MediaWiki software for keeping, collaboratively editing, and displaying structured data. SPARQL is used to make queries on it, and records are identified with Wikidata identifiers.

Links

 * Official site
 * Data Model Primer
 * API documentation