Welcome to InChI


The International Chemical Identifier

InChI is a structure-based chemical identifier, developed by IUPAC and the InChI Trust. It is a standard identifier for chemical databases that facilitates effective information management across chemistry.

InChI and InChIKey are open standards. They use unique machine readable strings to represent, store and search chemical structures. All the software and algorithms related to them are open source.

Latest InChI News

InChI In Action In Aachen - 24-25 July 2024 (June 6, 2024)

Technical meeting, focussing on organometallics, inorganics, stereochemistry and
programming issues.

Day 1 pm only
General overview / status overview (public web presentation – see below for registration link) (2-3pm CET)

Testing & GitHub

Group reporting: RInChI, Stereochem, Polymers, Inorganics

Directions of InChI
Compression/Hashing of InChI string
• Pain points/gaps of InChI
• InChI and legislation
• Potential opportunities in industry

Day 2
Inorganics prototype, inorganic stereochemistry, enhanced (organic) stereochemistry (am)
• Feedback on actual status of inorganics prototype
• Discussion: status of planned inorganic stereochemistry enhancements
• Discussion: status of planned “enhanced stereochemistry”
• Changes of the InChI format related to inorganics/organometallic enhancements and enhanced stereochemistry, need for additional stereochemistry layers

Architecture of InChI: MInChi, NInChI, RInChI (pm)
• Shared code stream?
• Common data input format? Adapted UDM format
• Application InChI deliveries
• Test environments and test data


InChI 1.07 release candidates - currently RC2 (June 6, 2024)

The team are clearing some further identified bugs and testing ahead of approval of this new 1.07 release. Meanwhile planning for the next major release is ongoing.


Catch up on progress and plans for InChI (April 21, 2024)

We held an online update on InChI on 26th March, covering current status and future roadmap for the standard:

Technical Update
InChI Subcommittee / Working Group Update
InChI Trust Organisational Update

View the recording: (Passcode: 2%9QJ%+y)


What is InChI and InChIKey?

InChI identifiers describe chemical substances in terms of layers of information – the atoms and their bond connectivity, tautomeric information, isotope information, stereochemistry and electronic charge. The InChIKey is a fixed length (27 character) condensed digital representation of the InChI that is not designed to be human-understandable.

InChI is a structure-based identifier, strictly unique, and non-proprietary, open source and freely accessible.

InChIKey is a hashed version of InChI which allows for a compact representation and for searching.

Where are InChI and the InChIKey used?

InChI is used by most of the large chemical databases and software applications handling many millions of chemical structures.

InChI enables the linking and interlinking of chemistry and chemical structures on the web and computer platforms.  By enhancing the discoverability of chemical structures, InChI advances the ‘FAIR Guiding Principles for scientific data management and stewardship’. FAIR was published in 2016 to provide guidelines to improve the Findability, Accessibility, Interoperability, and Reuse of digital assets.  InChI provides ‘Findability’ for chemical structures and extends Interoperability between platforms, both of which foster Accessibility and Reuse.

The InChI Trust

The InChI Trust is a charity that supports the development and promotion of the InChI standard. It works in partnership with IUPAC to update and release new extensions to and applications of InChI. The Trust is a membership organisation, governed by its Board of Trustees which includes representation from IUPAC.

The scientific design of the various tools and capabilities that comprise the InChI code are defined by the InChI Working Groups which are made up of volunteers from the InChI community with IUPAC oversight. These voluntary groups are each focused on specific areas of chemistry or tools within the InChI code. See Working Groups for details on each group and their membership.

The development of the code is coordinated by the Technical Director of the InChI Trust, together with the working groups, IUPAC and our development partners. Our development partners currently include RWTH Aachen (as part of NFDI4Chem, acknowledging funding from Volkswagen Stiftung and the Data Literacy Alliance – DALIA), and the Beilstein-Institut.

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