Recent years have seen the successful online publication of a number of virtual union catalogues for coinages from different fields of numismatics, for example Online Coins of the Roman Empire (OCRE) and PELLA. However, the development of such a resource for the coinage of pre-Roman Iron Age Europe presents a number of new challenges. Thus, there is no single universal standard reference work such as Roman Imperial Coinage that could provide a framework, but rather a wide range of often conflicting typologies covering individual coinages. Furthermore, some of the concepts used to describe Greek and Roman coinages, such as issuer, authority, mint and denomination cannot be applied in the same straightforward way to Iron Age coins. This paper will consider these challenges and discuss potential solutions that are needed in order to develop an Online Celtic Coinage.