- PubChem
Contains more than 10 million compound structures with their biological property information and 17 million records of substances.
- NIST Chemistry WebBook
Search for data on specific compounds in the Chemistry WebBook based on name, chemical formula, CAS registry number, molecular weight, chemical structure, or selected ion energetics and spectral properties.
- ChemIDplus
Dictionary of over 370,000 chemicals (names, synonyms, and structures). Includes links to NLM and other databases and resources.
- ChemBioFinder.com
ChemBioFinder.com is an online chemistry and biology reference database. 5 free searches before users are required to register. Limited access to linked material.
- ChemSpider
ChemSpider is a free chemical structure database providing fast text and structure search access to over 26 million structures from hundreds of data sources.
- Properties of Organic Compounds
Properties of Organic Compounds is a database that contains over 29,000 of the most commonly sought organic compounds, featuring physical data, spectral data, and structures.
- SureChem
Integrating patent chemistry into the scientific community. Free registration required.
- Agricola
Indexing for journals, books, etc. in agriculture, 1600s to present.