Reaxys (Elsevier)
Collection of databases: Reaxys (Beilstein and Gmelin handbooks of >75 million chemical substances, plus literature index including patents), Reaxys Medicinal Chemistry (>40 million chemical substances and bioactivity datapoints, plus literature index), PubChem (from NLM; >91 million chemical substances), eMolecules (chemical suppliers), LabNetwork (chemical suppliers), Sigma-Aldrich (chemical supplier).