MDL Chime is a free plugin used by web browsers to display the three-dimensional structures of molecules. It is part of the ISIS product line acquired by Symyx Technologies from scientific publisher Elsevier in October 2007. It is based on the RasMol code. Chime is used by a wide range of biochemistry web sites for the visualization of macromolecules. Many of these sites are linked to the World Index of Molecular Visualization Resources MolVisIndex.Org. Chime was also used until 2006 at the Protein Data Bank to examine structures stored there.