InChI Trust Website

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PRECISION FDA CHALLENGE: Crowdsourced Evaluation of InChI-based Tautomer Identification

The InChI Trust, the IUPAC Working Group on Tautomers, and the U.S. FDA call on the scientific community dealing with chemical repositories/data sets and analytics of compounds to test a modified InChI algorithm. The modified InChI was designed for advanced recognition of tautomers, against real chemical samples. Challenge Time Period: November 2022 – March 2023. CLICK HERE for more information.

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The International Chemical Identifier

InChI is a character string generated by computer algorithm, originally developed by the International Union of Pure and Applied Chemistry (IUPAC). InChI is a Standard Identifier for chemical databases and is essential for 21st century communication, enabling effective information management across chemistry.

IUPAC Division VIII established the InChI Subcommittee to develop the scientific rules for representing defined chemical structures, initially focusing on organic molecules.  For other aspects of chemical structures (tautomers, inorganic, organometallic, etc.), the Subcommittee has established Working Groups to extend the Standard to additional areas of chemistry.  The conceptual design and direction is decided by the IUPAC Working Groups which are made up of experts in the associated fields.  More information on the Working Groups is available here.

InChI with its associated InChIKey were developed as a non-proprietary and open international standard. The InChI algorithm turns chemical structures into unique machine readable strings. InChI and InChIKEY are used for describing, storing and searching chemical structures and all of the associated software components are non-proprietary and open source.

The InChI Trust

The InChI Trust is a UK charity that oversees the implementation and new rules developed and approved by IUPAC through the Working Groups.  The Trust aims to further expand the use the InChI standard with extended chemical and computational capabilities. The Trust also promotes the use of the InChI algorithm.

A broad community of scientists and developers continues to extend the InChI Standard. Much of this effort is contributed by our sponsors and supporters. Contact any of them or reach out directly to us at the InChI Trust for more information or with any questions.

What is InChI and InChI KEY?

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 in standard search engines like Google.

For more about the InChI standard CLICK HERE. See also our Wikipedia article.

Latest InChI News (View All InChI News)

October 23, 2023: InChI Poster at the CODATA Meeting in Salzburg Oct 23-26, 2023

  • Gerd Blanke will present a poster at the CODATA Meeting in Salzburg, Austria, the week of October 23, 2023. He will highlight some of the new additions to the InChI Standard that are in development and coming soon in the next release.

July 26, 2023: InChI Trust Announces Aug 12 Seminar Preliminary Agenda

  • The InChI Trust announced the preliminary agenda for the seminar it will hold the day before the ACS Meeting starts. On Aug 12, 2023 from 9am to 5pm Pacific time, InChI Trust will hold a seminar at the Hilton San Francisco Union Square in the HQ: Golden Gate 6 room. The preliminary agenda is available at

July 25, 2023: InChI Workshop on Inorganic Stereochemistry

  • A workshop on InChI and inorganic stereochemistry was held in Aachen Germany in May 2023. A summary of that meeting is now included here along with links to more details on the discussion and decisions. Learn more about the Inorganics Working Group at:

Where are InChI and InChI Key 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!

InChIKEY Implemented in Google

Google has implemented the ability to use an InChIKEY for queries. An InChIKEY can simple be embedded in a Google query and it will be used by Google to query for information on that specific chemical.

Google has implemented the ability to use an InChIKLEY for queries. An InChIKEY can simple be embedded in a Google query and it will be used by Google to query all the information related to that chemical structure. This includes most patents and a broad set of additional chemical databases.

related to that chemical structure. This includes most patents and a broad set of additional chemical databases.

InChI_Trust Twitter Feed

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InChI: Chicago ACS 21 Aug 2022

InChI In the Wild: Celebrating Over 20 years of InChI Development in Memory of InChI Developer Igor Pletnev

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