About the InChI Standard

A few general questions and answers about the InChI are supplemented by an extensive technical FAQ available here.

What is an InChI?

InChI is short for International Chemical Identifier.

InChIs are text strings comprising different layers and sublayers of information separated by slashes (/). Each InChI strings starts with the InChI version number followed by the main layer. This main layer contains sublayers for chemical formula, atom connections and hydrogen atoms. Depending on the structure of the molecule the main layer may be followed by additional layers e. g. for charge, stereochemical and/or isotop information.

History of InChI







