One of the largest online numismatic catalogues is hosted by Numista, serving as a knowledge base for coins, banknotes, medals, tokens, and other related items. The catalogue, numbering currently more than 280,000 types, is entirely free toaccess and addresses private collectors, museums, and researchers alike. The distinguishing features of Numista are (i) its collaborative nature, the catalogue being edited by its audience and (ii) its universal scope, aiming to record all numismatic items from all periods and places. This paper presents the Numista relational database, which contains tables for numismatic objects and their attributes, such as mints, materials, and engravers. The catalogue is accessible through the Numista website and through an application programming interface (API), which facilitates the exchange of information with other databases. Recently, Numista has started to implement linked data methodologies, and has semantic links to numismatic and general data sets.