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How to open .CW files on Windows

To open .CW files on Windows, install and open CU-Writer for Windows (the application associated with application/prs.cww for .cw/.cww files).

Step-by-step instructions

  1. Install and open CU-Writer for Windows (the application associated with application/prs.cww for .cw/.cww files).
  2. In File Explorer, double-click the .cw file; if it does not open, right-click → Open with → choose CU-Writer.
  3. If you need to use the file elsewhere, use CU-Writer’s export/save-as features (if available) to create a more widely supported format.

Alternative methods

  • Open .CW in a browser-based viewer if desktop apps fail.
  • Try opening .CW on Windows with a secondary app to rule out app-specific issues.
  • Convert .CW only with trusted tools when direct opening is not possible.

Common issues

Windows shows “Choose an app to open this file”

This usually happens when CU-Writer is not installed or the file association for .cw is missing.

  1. Install CU-Writer for Windows, then try opening the file again.
  2. Right-click the file → Open with → select CU-Writer; optionally set it as the default for .cw files.

The file is identified as application/prs.cww or has the .cww extension

The IANA registration for application/prs.cww lists both .cw and .cww as associated extensions, so you may see either extension or the MIME type label.

  1. Try opening it in CU-Writer regardless of whether the extension is .cw or .cww.
  2. Avoid changing extensions as a “fix”; use CU-Writer to open and then export if you need another format.

The file opens but shows garbled text or missing characters

CU-Writer is a Thai-capable word processor; incorrect fonts/encoding support or opening in non-matching software can lead to unreadable content.

  1. Open the file in CU-Writer (not a generic editor) to ensure correct rendering.
  2. If sharing, export from CU-Writer to a more widely supported document format to preserve readability on other systems.

Linux/macOS cannot find an application to open the file

Even if the system can map .cw/.cww to a MIME type, the required application (CU-Writer) is not commonly available on those platforms per the provided sources.

  1. Move the file to Windows and open it with CU-Writer.
  2. Ask the sender to export the file from CU-Writer into a more common format.

Security note

.cw/.cww is a document format associated with a specific application (CU-Writer); the main practical risk is opening untrusted files in a complex document parser. Prefer opening unknown files in a controlled environment.

Back to .CW extension page