InChI Software Downloads


InChI version 1 (software version 1.04) for Standard and Non-Standard InChI/InChIKey (September 2011)

This version now supports the chemical elements up to 112, copernicium (the last one which is currently recognized by IUPAC; support for elements 105-112 is newly added). The inchi-1 executable (both Windows and Linux versions) now allows the processing of multiple input files in a single run (common file name wildcards are recognized). In addition version 1.04 also fixes a number of minor bugs.

  • INCHI-1-DOC.zip – contains documentation related to InChI/InChIKey identifiers v. 1 and InChI software v. 1.04 (September 2011).
  • INCHI-1-BIN.zip – contains stand-alone executables for generating the InChI/InChIKey (Windows and Linux).
  • INCHI-1-API.zip – contains code, VC++ projects and gcc makefiles of command-line program inchi-1, as well as of InChI generation library (plus sample applications which use the Library).
  • INCHI-1-TEST.zip – contains the files representing various chemical structures and a simple test suite for InChI/InChIKey software.
    IUPAC / InChI Trust Licence No. 1.0 for the International Chemical Identifier (InChI) Software version 1.04: PDF Format / DOC Format

Each zip should be unpacked into a separate directory. For the details, see ‘RelNotes.pdf’ document in INCHI-1-DOC and the ‘readme.txt’ files in the respective directories.

Documentation for InChI software v. 1.04 (September 2011)

These are individual InChI software v. 1.04 documentation files from the INCHI-1-DOC.ZIP file for rapid access:

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:

InChI version 1 (software version 1.03) Source Code Documentation (March 2011)

The InChI Source Code Documentation provided by the InChI Trust:


Previous versions provided for reference


InChI version 1 (software version 1.03) for Standard and Non-Standard InChI/InChIKey (June 2010)

  • INCHI-1-DOC.zip – contains documentation related to InChI/InChIKey identifiers v. 1 and InChI software v. 1.03 (2010).
  • INCHI-1-BIN.zip- contains stand-alone executables for generating the InChI/InChIKey (Windows and Linux).
  • INCHI-1-API.zip – contains code, VC++ projects and gcc makefiles of command-line program inchi-1, as well as of InChI generation library (plus sample applications which use the Library).
  • INCHI-1-TEST.zip – contains the files representing various chemical structures and simple test suite for InChI/InChIKey software.
  • LICENSE.PDF – copy of GNU LGPL licence [pdf file]

Each zip should be unpacked into a separate directory. For the details, see ‘RelNotes.pdf’ document in INCHI-1-DOC and the ‘readme.txt’ files in the respective directories.

InChI version 1 (software version 1.02) for Standard InChI/InChIKey

InChI version 1 (software version 1.02beta) September 2007

  • inchi102b.zip – source code and Application Program Interface (API), stand-alone executable (cInChI), description of new features, with examples of using new functionality copy of GNU LGPL licence

InChI version 1 (software version 1.01) August 2006

  • InChI-1.zip – InChI version 1 (software version 1.01) documentation, and Windows and Linux (i386) executable programs
  • InChI-1-API.zip – InChI version 1 (software version 1.01) source code and Application Program Interface (API)
  • InChI-1-validation.zip – InChI validation protocol
  • Whats_New.pdf – What’s new in InChI software version 1.01