InChI Working Groups

Education/Academic/Training (OER)

Working Group Chair: Robert E. Belford

Working Group Members:  Bob Belford; Nathan Brown; Ehren Bucholtz; Jordi Cuadros; Tanya Gupta; Tina Qin; Vincent Scalfani; Martin Walker; Steven Wathen;  Andrew Cornell

The primary mission of the OER task group is to bring about a greater awareness of InChI in the education community, while also facilitating its use and adoption across other communities.  There are three major facets to this endeavor; creating original educational material, and creating  resources that allow educators and scientists to share material with others, with the latter being the mission of the OER website, and general outreach (running workshops, symposia, giving talks, posters, etc).

Extended Stereochemistry

Working Group Chair: Andrey Yerin

Working Group Members:  Andrey Yerin;  Gerd Blanke;  Burt Leland;  Jürgen Kammerer;  Clare Tovee;  Yulia Borodina;  Jane Frommer;  Nicki Davis; Per-Ola Norrby;  Jonathan M Goodman

The project is making progress and is investigating possible solutions for further consideration. These include enhanced stereo marks; tropisomers; longer allenes; etc.

Extended Tautomers

Working Group Chair: Marc C. Nicklaus

Working Group Members: Gerd Blanke; Evan Bolton; Alex M. Clark; Bret Daniel; Devendra Dhaked; Laura Guasch; Wolf; Dietrich Ihlenfeldt; Gregory Landrum; John W. Mayfield; Hitesh Patel; Roger Sayle; Dmitrii Tchekhovskoi

This group is studying how to extend tautomer handling in InChI. Of the 90 tautomeric transforms that were identified, six could be incorporated in an experimental version of the InChI  code (based on InChI version 1.06). See the report “Tautomers in InChI” <link> presented at the March 2021 NIH InChI Workshop <workshop link>.

InChI Resolver

Working Group Chair:  Markus Sitzmann

Is it possible to recalculate the InChI out of an InChIKey? No! The InChIKey is the hashed representation of its InChI. The hashing makes it impossible to go backwards from the InChIKey to the original InChI. To find a solution the “Resolver Protocol” project was started.

The InChI Resolver Protocol is a common API protocol which allows any InChI Resolver instance to be findable and browsable for an (automated) client system in a systematic, predefined manner.  It will also allow for the implementation of a network of federated InChI Resolvers


  • web resources providing data & information based on InChI become findable & interlinked on the web
  • their content is accessible in a generic way
  • (long-term) an autonomous client can find and collect information based in InChI

InChI Source Code Repository (GitHub) 

Working Group Chair: Gerd Blanke

Our aim has been to transition the InChI development environment to a more open and transparent model. This was even more critical following by the sad passing of Igor Pletnev, our primary developer, in late 2021.

Since then, much progress has been made transitioning the existing code to a GitHub environment, developing additional understanding of the code, fixing bugs and creating testing protocols that build on previous practice. This work has taken place at RWTH Aachen, supported by the NFDI4Chem project and the Volkswagen Foundation. The next ‘new’ version of InChI – rebuilding of the current version 1.06, cleaned-up and with additional bugfixes, is in testing and will be available for the IUPAC InChI Subcommittee and CPCDS to approve soon. The code now lives on GitHub – we are also working through the governance needed for this new development model aligned with IUPAC.


Organometallics/Inorganics Working Group Chair: Sonja Herres-Pawlis, Gerd Blanke

Working Group Members: Sonja Herres-Pawlis; Gerd Blanke;

Possible other members: Alex Clark; Andrey Yerin; Clare Tovee; Colin Batchelor; Dmitrii Tchekhovskoi; Evan Bolton; Ian Bruno; Jane Frommer; Jonathan Goodman; Richard Hartshorn; Steve Hellers; Thomas Doerner; Ulrich Schatzschneider; Yulia Borodina

The Working Group is discussing how a proposed representation of organometallic and inorganic compounds within InChI can be implemented.


Working Group Chair:  Hunter Moseley

Working Group Members: Hunter Moseley; Philippe Rocca-Serra; Reza Salek; Masanori Arita; Emma Schymanski

Develop enhanced specifications within the regular InChI standard for representing isotopologues and isotopomers. More specifically, augment the isotopic layer specifications of the regular InChI standard so that specific isotopologues, isotopomers, partial isotopomers, and isotopologue fragments can be represented by a single InChI string and used to identify isotope-informative analytical features.

Large Molecules

Working Group Chair: Evan Bolton

Working Group Members: Keith Taylor; Roger Sayle; John May; Noel O’Boyle; Daniel Lowe; Claire Bellamy; Anna Gaulton; Leah McEwen

A presentation titled ‘Progress towards “Large Molecule” support within InChI’ was given at a  recent (March 2021) NIH Workshop on InChI by Evan Bolton.


Working Group Chair:  Jonathan Goodman

Working group: Gerd Blanke, István Öri, Anthony Baston


  • A framework is been defined, based on InChI v1.06
  • Canonicalization and stereo differentiation under examination
  • Creating VInChI: provide a list of InChI and VInChI
  • Creating MarkInChI: currently hand-crafted by artisans


Working Group Chair: Leah McEwen

Working group:  Alex Clark, Antony Davies, John Duffus, Chris Jakober, Jon LaRue, Gerd Blank, Richard Hartshorn, Andrey Yerin

The IUPAC MInChI project defines a method to apply the IUPAC InChI identifier to describe what is definitively known about the chemical composition of a given mixed substance, generating an unambiguous machine-readable linear notation for mixed substances of uniform properties that can resolve to unique components. These requirements and guidelines allow for the generation of a unique computer-readable MInChI for chemical mixtures that can be used in chemical stock inventories and information systems based on the InChI standard.


Working Group Chair: Iseult Lynch

Working Group Members:  Iseult Lynch; Antreas Afantitis; Thomas Exner; Fred Klaessig; Nikolay Kochev; Martin Himly; Gergana Tancheva; Jaleesia Amos; Mark Wiesner; Egon Willighagen; Alex Clarke; Gerd Blanke; Jonathan Goodman; Vladimir Lobaskin; John Rumble; Georgia Melagraki; Tassos Papadiamantsis; Harry Sarimveis; Dieter Maier; Effie Marcoulaki; Kostas Blekos; Steve Heller; Clyde Daly; Michael Schwartz; Nikki Davis; Diego Martinez; Nikolaos Nikoloudakis; Ioannis Xiarchos

This project proposes to identify a specific nanomaterial/nanoform through an extension of the IUPAC InChI called NInChI.  The approach is to encode information

This project proposes to identify a specific nanomaterial/nanoform through an extension of the IUPAC InChI called NInChI.  The approach is to encode information such as composition, size, shape, surface chemistry, etc. As nanomaterials are particulates, there is an intimate relationship between the core and surface compositions that challenges traditional naming conventions, thereby limiting information exchange among scientists and computational modelers across academia, industry and regulatory agencies. Leveraging best practices with other InChI working groups e.g. Mixture InChI, Reaction InChI & Polymer InChI are planned.

QR Codes

Working Group Chairs: Jeremy Frey and Richard Hartshorn

Working Group Members:  Jeremy Frey; Richard Hartshorn; Leah McEwen

A proof-of-principle implementation was made available:

A revised draft of the InChI QR code specification document, formulated as an IUPAC  Recommendation, was prepared and sent out for approval. The recommendation was then revised and submitted to PAC where it is currently under review.


Working Group Chair: Gerd Blanke

Working group: Gerd Blanke, Günter Grethe, Gudrun Gygli, Hans Kraut, István Öri,  Jan Holst Jensen, Jonathan Goodman, Nicki Davis

A standard machine-readable, indexable and searchable representation of chemical reactions based on the IUPAC International Chemical Identifier (InChI).

Version 1.0 of the Reaction InChI is the current version, with RInChI 1.1 in test as of end-2023. See InChI Downloads