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How to open .IST files on Windows

To open .IST files on Windows, if the file is from an installer-building workflow, install and open it with Flexera InstallShield (FileInfo.com lists InstallShield as the primary program for .IST).

Step-by-step instructions

  1. If the file is from an installer-building workflow, install and open it with Flexera InstallShield (FileInfo.com lists InstallShield as the primary program for .IST).
  2. If it is from a CCDC IsoStar/IsoStar server workflow, open it through the IsoStar tools/environment that produced it; if you received it via a browser, download it and ensure the server is configured to serve it as chemical/x-isostar.

Common issues

The .IST file opens as plain text in a browser (IsoStar server issue)

CCDC notes this can happen when an IsoStar server is not serving scatterplot-related content with the correct MIME type.

  1. Confirm your web server sends the .ist content as chemical/x-isostar (CCDC provides an Apache mime.types mapping example).
  2. After fixing MIME configuration, reload the page or re-download the file and open it through the IsoStar workflow that expects chemical/x-isostar.

Windows shows “Windows can’t open this file” or opens the wrong program

This commonly occurs when InstallShield is not installed or when the file is not an InstallShield template (because .IST is used by more than one format).

  1. Check the file’s origin (e.g., from a software installer project vs. CCDC/IsoStar context).
  2. If it is an InstallShield template, install Flexera InstallShield and open it from within the application.
  3. If it is IsoStar-related, do not force-open it in a text editor; open it using the IsoStar environment instead.

FileInfo or metadata indicates one use, but the file content doesn’t match

Because .IST is ambiguous, some systems may mislabel it; the correct handler depends on the producing application.

  1. Verify with the sender which program created the file (e.g., InstallShield vs. IsoStar).
  2. If you control the server delivering the file in an IsoStar context, ensure the MIME mapping is set to chemical/x-isostar.

Security note

Treat unknown .IST files as potentially risky because the extension is ambiguous; do not assume it is a harmless “archive” and avoid opening it with random tools.

Back to .IST extension page