The IUPAC International Chemical Identifier (InChI) is a non-proprietary identifier for chemical substances that can be used in printed and electronic data sources. It is derived solely from a structural representation of that substance, such that a single compound always yields the same identifier.

Prefix

inchi

Keywords

centrally registered identifier chemical descriptor chemical entity chemical structure cheminformatics chemistry knowledge and information systems molecular entity molecular structure

Links

Homepage Repository

Contact

Stephen R. Heller   0000-0002-5538-8482

Pattern for Local Unique Identifiers

Local identifiers in InChI should match this regular expression:
^InChI\=1S?\/[A-Za-z0-9\.]+(\+[0-9]+)?(\/[cnpqbtmsih][A-Za-z0-9\-\+\(\)\,\/\?\;\.]+)*$

Example Local Unique Identifier

InChI=1S/C2H6O/c1-2-3/h3H,2H2,1H3   Resolve

Pattern for CURIES

Compact URIs (CURIEs) constructed from InChI should match this regular expression:
^inchi:InChI\=1S?\/[A-Za-z0-9\.]+(\+[0-9]+)?(\/[cnpqbtmsih][A-Za-z0-9\-\+\(\)\,\/\?\;\.]+)*$

Example CURIE

inchi:InChI=1S/C2H6O/c1-2-3/h3H,2H2,1H3

Publications

• 2021 InChI version 1.06: now more than 99.99% reliable
• 2015 InChI, the IUPAC International Chemical Identifier
• 2015 Many InChIs and quite some feat
• 2024 InChI isotopologue and isotopomer specifications

The metaregistry provides mappings between the Bioregistry and other registries. There are 5 mappings to external registries for this resource with 3 unique external prefixes.

A provider turns a local unique identifiers from a resource into a URI. Many providers are also resolvable as URLs (i.e., they can be used in a web browser).

The local unique identifier InChI=1S/C2H6O/c1-2-3/h3H,2H2,1H3 is used to demonstrate the providers available for InChI. A guide for curating additional providers can be found here.

Additional providers curated in the Bioregistry are listed here. These are typically inherited from Identifiers.org or Prefix Commons, and need extra curation.