InChIs, are machine-readable, alpha-numeric character strings first developed by International Union of Pure and Applied Chemistry (IUPAC),  Now the InChI Trust is carrying on the work to develop and expand the algorithms for open source accessibility of even more chemical structures.

From Today’s Knowledgespeak Newsletter:

"The InChI algorithm turns chemical structures into machine-readable strings of information. InChIs are unique to the compound they describe and can encode absolute stereochemistry. A simple analogy is that InChI is the bar-code for chemistry and chemical structures. The InChI format and algorithm are non-proprietary and the software is open source, with ongoing development done by the community."

"Since its launch in 2005, widespread take-up of InChI standards by public databases and journals has been observed. Today, there are more than 100 million InChIs in scientific literature and products. Numerous databases, journals and chemical structure drawing programs have incorporated the InChI algorithm. These include the NIST WebBook and mass spectral databases, the NIH/NCBI PubChem database, the NIH/NCI database, the EBI chemistry database, ChemSpider and Symyx Draw."