Open Source, Distributed, Scalable, Lightning Fast Graph Database
The open source graph database built for super large-scale graphs with milliseconds of latency.
, that provides backend services to query hosted KG. It also supports querying KG using a combination of SQL and SPARQL. On top of it, a lot of open-source KG like DBpedia are hosted on Virtuoso.
DBpedia: is a crowd-sourced community-based effort to extract structured content from the information present in various Wikimedia projects.
Freebase: a massive, collaboratively edited database of cross-linked data. Touted as “an openly shared database of the world’s knowledge”. It was bought by Google and used to power its own KG. In 2015, it was finally discontinued.
OpenCyc: is a gateway to the full power of Cyc, one of the world’s most complete general knowledge base and commonsense reasoning engines.
Wikidata: is a free, collaborative, multilingual database, collecting structured data to provide support for Wikimedia projects.
YAGO: huge semantic knowledge base, derived from Wikipedia, WordNet, and GeoNames.