@mindcrime has put a pretty extensive list and explanation. The things is, you are probably looking for a solution that does the reconciliation of data arrivin

@mindcrime has put a pretty extensive list and explanation. The things is, you are probably looking for a solution that does the reconciliation of data arriving from multiple sources and formats for you and preferably exposes it over an easy to use API. You can try http://unigraph.io http://unigraph.io, the API Sandbox (GraphQL) is available at: http://u01.unigraph.rocks http://u01.unigraph.rocks and an extensive documentation covers it at: https://github.com/unigraph/docs/wiki https://github.com/unigraph/docs/wiki Currently Unigraph combines data from: - wikidata - geonames - freebase - crunchbase - SEC EDGAR - Companies House (UK). A datadump is on its way and more sources will be added soon. Disclaimer: I am building Unigraph, precisely for the reason of the question: "An open alternative to GKG".