Presentation at the Netherlands Metabolomics Days. Abstract: We here discuss Wikidata, a young sister project of Wikipedia but with one big difference: it is a machine readable database, making it far more useful for interoperability of molecular databases in systems biology. Thanks to the Wikidata:WikiProject Chemistry community, there is a growing amount of information about chemical compounds: Wikidata currently has over 150 thousand chemical compounds, of which more than 95% is associated with InChIKeys and has more than 70 thousand CAS registry numbers. Ongoing work by this WikiProject includes capturing chemical classes and chemical compounds in the various Wikipedia’s as machine readable data. We recently reported about ongoing efforts of using Wikidata and Scholia for chemical knowledge.