Download Latest InChI Standard Software

InChI Core Software

Below are the current versions of both the InChI core software (v1.06) and the reaction InChI / RInChI (v.1.00)

Download InChI version 1 (software version 1.06) for Standard and Non-Standard InChI/InChIKey (15 December 2020)

This package contains InChI Software version 1.06 (Winter 2020).

For an earlier version CLICK HERE.

Please use the SourceForge inchi-discuss list for any comments (register via

InChI Software v. 1.06 includes several additions and modifications to previous versions; it is a combination of “bugfix release” and “feature release”.

What is new:

– security-related bugfixes;
– a number of other bugfixes and minor improvements;
– experimental support for pseudo element (Zz, or “star”) atoms;
– modified experimental support of InChI/InChIKey for regular single-strand polymers (explicit pseudo atoms are used);
– minor update to InChI API Library;
– optional support of Intel(R) Threading Building Blocks scalable memory allocators;
– several convenience features and corresponding software options.

For more details, please check the documents included in the distribution (all in PDF format):

– RelNotes (a brief description of novel and changed features)
– CHANGELOG (list of changes relative to the previous release)
– KNOWNISSUES (list of known issues)
– LICENCE (IUPAC/InChI Trust software licence)
– InChI_UserGuide (software user’s guide)
– InChI_API_Reference (programmer’s reference for API library)
– InChI_TechMan (technical manual on InChI identifier)

Download the RInChI version 1.00 (23 March 2017)

This package contains the RInChI software release version 1.00

In 2011, the first prototype of RInChI was introduced as version 0.02 based on Python programming (Grethe, Goodman, & Allen, 2013). To make the resulting libraries comparable with InChI deliveries, to increase the search ability of RInChIKeys in the Web by the introduction of the Web-RInChIKey and to fix a number of bugs and development gaps in the former version this new version (version number 1.00) has been created.

InChI FAQ (May 2012)

The InChI FAQ is an attempt to answer common questions on InChI-related concepts and the structure and meaning of InChIs. Where possible it quotes directly from the official IUPAC/InChI Trust sites and the distribution.

The original ‘Unofficial InChI FAQ’ was created by Nick Day at the Unilever Centre, Department of Chemistry, Cambridge University. In 2011, the document has been revised and updated, with the permission of Nick Day, by the InChI Trust to take into account recent developments of InChI itself and the InChI software. It has the status of an official FAQ.

The description of InChI in this FAQ corresponds now to the latest software release of Fall 2011 and to the latest official documentation. Most of the examples use Standard InChI & InChIKey.

The InChI FAQ is available in three formats:

Find out about the Certification Suite here.