Provides access to structure and nomenclature authority files used for the identification of chemical substances cited in National Library of Medicine (NLM) databases, including the TOXNET system. This database contains over 379,000 chemical records, of which over 257,000 include chemical structures, and is searchable by Name, Synonym, CAS Registry Number, Molecular Formula, Classification Code, Locator Code, and Structure. A structure searching option is available.

ChemSpider links together compound information across the web, providing free text and structure search access of millions of chemical structures. With an abundance of additional property information, tools to upload, curate and use the data, and integration to a multitude of other online services, ChemSpider is the richest single source of structure-based chemistry information. It is provided to the community by the Royal Society of Chemistry.

The DrugBank database is a unique bioinformatics and cheminformatics resource that combines detailed drug (i.e. chemical, pharmacological and pharmaceutical) data with comprehensive drug target (i.e. sequence, structure, and pathway) information.

PubChem is a database of chemical molecules. The system is maintained by the National Center for Biotechnology Information (NCBI), a component of the National Library of Medicine, which is part of the United States National Institutes of Health (NIH).

WolframAlpha is a computational database/search engine that interprets natural language queries, returning dynamic answers. Although still in development, it currently "...contains 10+ trillion pieces of data, 50,000+ types of algorithms and models, and linguistic capabilities for 1000+ domains."