Welcome to the InChI Trust Website


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)

August 25, 2022: InChI in the Wild: Celebrating Over 20 years of InChI Development in Memory of InChI Developer Igor Pletnev

  • This symposium honoring the many contributions of Igor Pletnev to the InChI project was held as part of the ACS Chicago 2022 meeting on Sunday August 21. Also covered were many research and development efforts to extend the InChI standard into additional areas of chemistry. The slide decks for these presentations are now available here.

July 1, 2022: Research Assistant/Associate - Software Development Position Open

  • Professor Dr. Sonja Herres-Pawlis, Institute of Inorganic Chemistry at RWTH Aachen University, has announced an open Reseach Assisstant position. The work will include further development of the IUPAC International Chemical Identifier (InChI), documentation of the programming developments and testing of extensions. The research group investigates topics in bioinorganic chemistry, sustainable polymerization catalysis, coordination chemistry and catalytic applications.

    More details on the position or to apply, Click HERE.

June 16, 2022: The InChI Trust Session at the Fall 2022 ACS Meeting in Chicago

  • The InChI Trust has set up an all day session at the August 2022 ACS Meeting in Chicago. The session will cover the InChI standard as well as many extensions to the standard that are under development. The details of the session can be found on this webpage.

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

The InChI community held a session at the ACS Fall Meeting 2022 in Chicago on Sunday entitled "InChI in the Wild" in memory of Igor Pletnev, long-time InChI developer. The slide decks from the excellent presentations are available on our website at https://www.inchi-trust.org/inchi-session-at-acs-chicago-on-21-august-2022-2/.

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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

InChI Videos

About us: WHO ARE WE ?

The diverse group of scientists and developers that contribute to the InChI projects come from industry, academia and government. They participate in one or more of the following groups:

Upcoming Events of Interest.  (See Full List)

September 29, 2022 – September 29, 2022

Chemaxon User Group Meeting


Chemaxon will hold its annual User Meeting in Boston on September 29th. The one day event will run in between 9 AM and 5 PM, with a gala dinner right after the official program. For more information or to register visit https://chemaxon.com/events/chemaxon-user-group-meeting-boston-2022.

October 18, 2022 – October 19, 2022

BioIT World Europe, Berlin

In Person

Join Distinguished Members of the Bio-IT Community in Berlin, Germany this October to Explore the Intersection of IT and Life Sciences . There will be 5 In-Depth Bio-IT Focused Conference Tracks: R&D in Pharma; AI for Pharma; Storage Infrastructure & Cloud Computing; Data Management; Bioinformatics. Bio-IT World has united a community of leading life sciences, pharmaceutical, clinical, healthcare, informatics, and technology experts in the fields of biomedical research, drug discovery & development, and healthcare from around the world. Join your colleagues for updates from inspiring keynotes, more than 60 presentations across five tracks, and 2 days of interactive discussion and networking.


No InChI Participation

January 9, 2023 – January 11, 2023

AnalytiX-2023: The 9th Annual Conference of AnalytiX-2023, Sapporo, Japan

In Person

AnalytiX, since 2012, has been attracting more than 3,000 participants from over 50 countries and regions. AnalytiX-2023 will provide participants scientific exchanges and frontier information in the research fields of Analytical Chemistry. World-class business & academic speakers will discuss the challenges and opportunities in the parallel sessions.

Recent Publications and Presentations (See Full List)

Overview Papers – most recent  (See Full List)

InChIs and Registry Numbers
Leigh, Jeffrey
J Cheminform 13 40 (2021).
DOI: https://doi.org/10.1515/ci.2012.34.6.23
The Status of the IUPAC InChI Chemical Structure Standard
Boucher, R.; Heller, S.; McNaught, A.
Chem Int 39 (3) 47–47 (2017).
DOI: https://doi.org/10.1515/ci-2017-0316
InChI, the IUPAC International Chemical Identifier.
Heller, Stephen R.; McNaught, Alan; Pletnev, Igor; Stein, Stephen; Tchekhovskoi, Dmitrii
J Cheminform 7 23 (2015).
DOI: https://www.doi.org/10.1186/s13321-015-0068-4
Many InChIs and Quite Some Feat
Warr, Wendy A.
J Comput Aid Mol Des 29 (8), 681–694 (2015).
DOI: https://doi.org/10.1007/s10822-015-9854-3
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InChI Development Papers – most recent (See Full List)

SELFIES and the future of molecular string representations
Mario Krenn , Qianxiang Ai , Senja Barthel , Nessa Carson , Angelo Frei , Nathan C. Frey , Pascal Friederich , Theophile Gaudin , Alberto Alexander Gayle , Kevin Maik Jablonka , Rafael F. Lameiro , Dominik Lemm , Alston Lo Seyed Mohamad Moosavi , Jos ́e Manuel Napoles-Duarte , AkshatKumar Nigam, Robert Pollice , Kohulan Rajan , Ulrich Schatzschneider , Philippe Schwaller Marta Skreta , Berend Smit , Felix Strieth-Kalthoff , Chong Sun , Gary Tom , Guido Falk von Rudorff , Andrew Wang , Andrew White Adamo Young , Rose Yu , and Alan Aspuru-Guzik
physics.chem-ph 31 Mar 2022.
DOI: https://arxiv.org/pdf/2204.00056.pdf
ABC-Net: a divide-and-conquer based deep learning architecture for SMILES recognition from molecular images
XC Zhang, JC Yi, GP Yang, CK Wu, TJ Hou, DS Cao
Briefings in Bioinformatics 23, (2022) 2, bbac033.
DOI: https://doi.org/10.1093/bib/bbac033
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AI/ML Papers Citing InChI – most recent (See Full List)

Bayesian multi-model-based 13C15N-metabolic flux analysis quantifies carbon-nitrogen metabolism in mycobacteria
Khushboo Borah, Martin Bey, Ye Xu, Jim Barber, Catia Costa, Jane Newcombe, Khushboo Borah, Martin Bey, Ye Xu, Jim Barber, Catia Costa, Jane Newcombe, Axel Theorell, Melanie J Bailey, Dany JV Beste, Johnjoe McFadden, Katharina Nöh
bioRxiv preprint 2022.
DOI: https://doi.org/10.1101/2022.03.08.483448
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Scientific Papers Citing InChI – most recent (See Full List)

OntoPESScan: An Ontology for the Exploration of Potential Energy Surfaces
Angiras Menon, Laura Pascazio, Daniel Nurkowski, Feroz Farazi, Sebastian Mosbach, Jethro Akroyd, Markus Kraft
Cambridge Centre for Comp Chem Eng preprint, 2022.
DOI: https://como.ceb.cam.ac.uk/media/preprints/c4e_am2145_preprint_294.pdf
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Drug Discovery Papers Citing InChI – most recent (See Full List)

Data Centric Molecular Analysis and Evaluation of Hepatocellular Carcinoma Therapeutics Using Machine Intelligence-Based Tools
Rengul Cetin-Atalay; Deniz Cansen Kahraman; Esra Nalbat; Ahmet Sureyya Rifaioglu; Ahmet Atakan; Ataberk Donmez; Heval Atas; M. Volkan Atalay; Aybar C. Acar; Tunca Doğan
J Gastrointestinal Cancer (2021)
A computer-aided drug design approach to discover tumour suppressor p53 protein activators for colorectal cancer therapy
Rui P.S. Patrício, Paula A. Videirab, Florbela Pereira
Bioorganic & Medicinal Chemistry 53, 116530 (2022).
DOI: https://doi.org/10.1016/j.bmc.2021.116530
De Novo Molecular Design with Chemical Language Models
Grisoni, F., Schneider, G.
Artificial Intelligence in Drug Design (2022).
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InChI OUTREACH  will be published on a regular basis every 2 to 3 months.  We will include the latest news, topics of interest, discussions on various aspects of InChI.  Click on the image below of the first issue to view and download it.

CLICK HERE to subscribe to future issues of InChI OUTREACH.