- WolframAlpha - Computational Knowledge Engine (You have to try it, trust me!)
- NIST Chemistry WebBook - Thermochemical, thermophysical, and ion energetics data.
- BRENDA - Enzyme functional data.
- SDBS - Spectral database for organic compounds.
- RCSB PDB - Protein Databank containing biological macromolecular structures.
- NDB - Nucleic Acid Database of three-dimensional structural information.