The Wikipedia sister project that is a free repository of structured data is Wikidata.
Launched on 29 October 2012, Wikidata is a collaboratively edited, multilingual knowledge graph hosted by the Wikimedia Foundation. Instead of primarily storing prose articles, it stores machine-readable information about people, places, organizations, scientific concepts, works, and countless other subjects. Each item has a persistent identifier called a QID, such as Q42 for Douglas Adams.
Wikidata was first created to centralize interlanguage links between Wikipedia editions, then expanded to provide shared data for infoboxes and other Wikimedia projects. Its data is released under the Creative Commons CC0 public-domain dedication, allowing Wikimedia and outside projects to reuse it freely. Researchers and developers can query the database using the Wikidata Query Service and the SPARQL query language.
A common mix-up is Wikimedia Commons, which is a media repository for images, audio, video, and other files. Wikinews publishes news, and Wikibooks hosts collaboratively written books. Wikidata’s distinctive role is organizing facts and relationships in structured, reusable form rather than presenting them mainly as encyclopedia articles.