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.CSF file extension

To open .CSF files on Windows, install Open Babel (the command-line tool commonly named "openbabel" or "obabel").

To open a .CSF file, use a chemistry/cheminformatics tool that supports the CAChe MolStruct (CAChe MolStruct CSF) format—most commonly Open Babel. On mobile, there is usually no practical native support, so transfer the file to a desktop and convert it to a more common chemistry format.

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Last updated: April 30, 2026 · Reviewed by Julian Stricker

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .CSF files

Use these platform-specific instructions to open .CSF files safely.

Windows

  1. Install Open Babel (the command-line tool commonly named "openbabel" or "obabel").
  2. Try converting the file to a widely supported chemistry format (for example, use Open Babel to convert .csf to another format that your viewer/editor supports).
  3. If conversion fails, verify whether your .CSF is actually a CAChe MolStruct file (chemical/x-cache-csf) and not a different, unrelated .CSF type.
Full Windows guide

Mac

  1. Install Open Babel (often used from the Terminal).
  2. Use Open Babel to convert the .CSF into a more commonly readable chemistry format and then open that output in your preferred chemistry viewer/editor.
  3. If Open Babel cannot read the file, note that CAChe MolStruct support is documented as write-only in some references; you may need the originating CAChe tooling or an alternative reader.
Full Mac guide

Linux

  1. Install Open Babel (CLI tool).
  2. Convert the .CSF to another chemistry format using Open Babel and open the converted output with your chemistry software.
  3. If the file won’t import, check whether your Open Babel build supports reading this particular .CSF variant (some references describe the format support as write-only).
Full Linux guide

iOS

  1. There is usually no practical native iOS support for CAChe MolStruct .CSF files; transfer the file to a desktop system and convert it with Open Babel.
Full iOS guide

Android

  1. There is usually no practical native Android support for CAChe MolStruct .CSF files; transfer the file to a desktop system and convert it with Open Babel.
Full Android guide

Security notes

  • .CSF in this context is a data file (chemical structure), not an executable format, but opening it still relies on parsers—avoid using obscure or untrusted converters/viewers for files from unknown sources.
  • Prefer well-known, maintained tooling (for example, Open Babel) when importing or converting chemical structure files, since complex parsers can have vulnerabilities.
  • If a .CSF file arrives unexpectedly or from an untrusted source, validate what it is (e.g., expected chemical structure content) before processing it in your toolchain.

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Can't open this file?

These are the most common causes and fixes when .CSF files fail to open.

Common reasons

  • No app can open the .CSF file
  • Open Babel cannot read the .CSF file
  • File opens but appears empty or incorrect after conversion

Fix steps

  1. Confirm the file came from a chemistry/molecular modeling workflow (CAChe MolStruct).
  2. Use Open Babel to convert it to a more common chemistry format and open the converted result.

OS-specific troubleshooting

What is a .CSF file?

.CSF (in this context) refers to the CAChe MolStruct chemical structure format, sometimes described as “CAChe MolStruct CSF.” References list its MIME type as chemical/x-cache-csf. Open Babel supports this format, but documentation notes it as write-only, meaning it may be used primarily as an output/export format rather than reliably readable input.

Background

In chemistry and molecular modeling workflows, .CSF is associated with CAChe MolStruct, a chemical structure file format referenced in chemical file format listings and MIME type tables as “CAChe MolStruct CSF.” It is used to store molecular structure data for exchange or downstream processing in cheminformatics pipelines.

In practice, many users interact with .CSF via format-conversion tools. Open Babel (and software that relies on it) lists support for “cache — CAChe MolStruct file,” and both Open Babel documentation and Molekel’s format list indicate it may be write-only, which affects how you “open” such files: you may need to convert from another format into CSF, or if you have a CSF file, you may need a tool/library that can read it (not always available in common desktop GUI apps).

Because file extension meanings can be ambiguous, if your .CSF file did not come from a chemistry or molecular modeling context, confirm its origin with the sender or the generating application. The guidance below focuses on the CAChe MolStruct chemical structure meaning, which is the one supported by the provided sources.

Common MIME types: chemical/x-cache-csf

Further reading

Authoritative resources for more details on the .CSF format.

Common .CSF issues

No app can open the .CSF file

Many systems don’t recognize .CSF as a common end-user format. In chemistry contexts it is typically handled by specialized tooling, often via conversion.

  1. Confirm the file came from a chemistry/molecular modeling workflow (CAChe MolStruct).
  2. Use Open Babel to convert it to a more common chemistry format and open the converted result.

Open Babel cannot read the .CSF file

Open Babel documentation and other references list CAChe MolStruct as write-only in some contexts, so your file may not be readable even if the format is known.

  1. Check whether your goal is to create/export CSF (write) versus import CSF (read).
  2. If you must read it, try obtaining the original software/workflow that produced the file, or ask for the data in a different export format.

File opens but appears empty or incorrect after conversion

Conversion quality depends on how completely the structure information is represented and whether the converter supports all fields/variants.

  1. Convert to more than one target chemistry format and compare results to detect information loss.
  2. If possible, request a different export format from the source system that better preserves the needed properties.

FAQ

What does .CSF usually mean?

In the provided sources, .CSF is associated with the CAChe MolStruct chemical structure format (“CAChe MolStruct CSF”), with MIME type chemical/x-cache-csf.

Is there a MIME type for .CSF?

Yes. References list chemical/x-cache-csf for CAChe MolStruct CSF.

Why do some tools say CAChe MolStruct is write-only?

Open Babel documentation and Molekel’s format list describe CAChe MolStruct support as write-only, meaning the tool may be able to produce CSF output but not reliably import/read CSF files.

Can I open .CSF on iPhone or Android?

Typically not in a practical way for CAChe MolStruct. The usual workflow is to move the file to a desktop system and convert it with Open Babel into a more commonly supported format.

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