ChemSpider

ChemSpider is a free chemical structure database and search engine developed and maintained by the Royal Society of Chemistry. Launched in 2007, it aggregates chemical structures and related information from a wide range of data sources to provide centralized access for researchers. The service is designed to facilitate rapid structure- and property-based queries and to connect users with primary data records.

Users can draw chemical structures or enter text-based identifiers to search. Available search modes include substructure search, exact structure search, similarity search, and property-based queries. Each record can display identifiers such as InChI, InChIKey, and SMILES, as well as molecular formula, molecular weight, and other physicochemical properties, with links to external sources. Structures are stored with a unique ChemSpider ID (CSID). The platform provides data linked to source records from multiple publishers and databases, with licensing varying by source.

ChemSpider offers programmatic access through a web API, enabling developers to query structures and retrieve data within software workflows. Registered users can save compounds and organize them into personal libraries; the service also supports accessing and exporting records in formats permitted by the source terms. As a community resource, ChemSpider facilitates data discovery and cross-referencing with other databases.

ChemSpider is widely used in chemical informatics, medicinal chemistry, and related fields for rapid access to structural information and for data integration with other resources. It serves as one of several major databases that researchers consult for compound information and structure searching.