Freebase is a free, knowledge graph with millions of people, places, and things. Freebase contains tens of millions of topics, thousands of types, and tens of thousands of properties. By comparison, English Wikipedia has over 4 million articles.This app doesn't have any features at the moment.Discontinued
According to https://developers.google.com/freebase/ the API has been shut down, but there are still data-dumps available.
OpenCyc is a cut-down open version of the Cyc technology, the world's largest and most complete general knowledge base and commonsense reasoning engine. Cycorp, the builders of Cyc, have set up an independent organization, OpenCyc.Discontinued
distribution was discontinued in early 2017