Today ChemSpider (www.chemspider.com) is one of the community’s primary online resources for chemists. Now hosting over 28 million unique chemical compounds linked to over 400 data sources, ChemSpider offers its users a structure centric platform facilitating access to publications and patents, experimental and predicted property data, spectral data and many other forms of data and information that can benefit a chemist. ChemSpider is a crowdsourcing platform allowing the community to contribute data directly to the database by allowing the deposition and sharing of structure data, properties, spectra and reaction syntheses. The crowdsourcing also allows for the annotation and curation of existing data thereby allowing the community to assist in the much-needed curation and validation of chemistry data on the internet. This work is imperative in order to provide the chemistry underpinnings to semantic web projects such as Open PHACTS (www.openphacts.org) of which Merck is sure to benefit when it is released to the community. This presentation will provide an overview of the ChemSpider platform and will also examine the challenges of dealing with heterogeneous data quality when attempting to provide a rich resource of data for the community. If you use the internet to research chemistry based data this presentation will be an essential guide to how to source high quality data.