Page 1 of 37 Public Chemical Compound Databases Antony J. Williams Address: ChemZoo Inc., 904 Tamaras Circle, Wake Forest, NC-27587 Corresponding Author:antony.williams@chemspider.com PHONE: 919 341-8375 The internet has fast become the first port of call for all searches. The increasing array of chemistry-related resources now available provides chemists a direct path to the discovery of information, one previously accessed via library services and limited to commercial and costly resources. The diversity of information available online is expanding at a dramatic rate and a shift to publicly available resources offers significant opportunities in terms of the benefit to science and society. While the data available online do not generally meet the quality standards available from manually curated sources there are efforts afoot to gather scientists and “crowd source” an improvement in the quality of available data. This article will discuss the types of public compound databases available online, provide a series of example databases and focus on the benefits and disruptions associated with the increased availability of such data and integrating technologies to data-mine the available information. Keywords Public databases, chemical structure databases, Open Data, chemoinformatics, data mining, internet chemistry, Wikis, blogs,