Jmol
An interactive viewer for three-dimensional chemical structures.
...Jmol can read many file types, including PDB, CIF, SDF, MOL, PyMOL PSE files, and Spartan files, as well as output from Gaussian, GAMESS, MOPAC, VASP, CRYSTAL, CASTEP, QuantumEspresso, VMD, and many other quantum chemistry programs. Files can be transferred directly from several databases, including RCSB, EDS, NCI, PubChem, and MaterialsProject. Multiple files can be loaded and compared. A rich scripting language and a well-developed web API allow easy customization of the user interface. Features include interactive animation and linear morphing. ...