* The CAS database is the most comprehensive repository for data on organic compounds. The search tool SciFinder is offered.
* The Beilstein database contains information on 9.8 million substances, covers the scientific literature from 1771 to the present, and is today accessible via Reaxys. Structures and a large diversity of physical and chemical properties are available for each substance, with reference to original literature.
* PubChem contains 18.4 million entries on compounds and especially covers the field of medicinal chemistry.
A great number of more specialized databases exist for diverse branches of organic chemistry.