The interface has the following features: 1) molecular similarity search. 2) substructure search. 3) pattern search. 4) lookup by ZINC ID; 5) lookup by supplier code; 6) lookup multiple SMILES; 7) database subset selection and download. 8). select molecules at random, 9) a shopping cart metaphor for organizing, curating, and preparing sets of molecules for purchase. Most features are available via the command line using curl or wget (see Methods) as well as via a web interface (Figure ). Commercially available molecules that are disclosed on the internet may not be patented, we are advised, and thus some database subsets including ZINC-22 require that the user logs in. To further prevent public access, a second level of authentication is required to access private databases (see Supporting Information S0). We take up each feature in sequence.