Abstract An increasing number of structured knowledge bases have become available on the Web, enabling many new forms of analyses and applications. However, the fact that the data is being published by different parties with different vocabularies and ontologies means that there is a high level of heterogeneity and no common schema. This paper presents Klint, a web-based system that automatically creates mappings to transform knowledge as provided by the sources into data that conforms to a large unified schema. The user can review and edit the mappings with a streamlined interface. In this way, Klint allows for human-level accuracy with minimum human effort.