What is a CHW File?

How to Open, Edit, & Convert CHW Files

Picture of the CHW file icon

A file with the CHW file extension is a Compiled Help Index file. It's created when multiple Compiled HTML Help (.CHM) files are merged together.

CHM files are help documents used by some programs to store questions and answers about how a program works or what the different options mean. CHM files are saved in the HTML format, so they can include text, hyperlinks, and images, and are generally viewable in any web browser.

CHW files, then, are used to keep a table of contents of the information in the different CHM files as well as references to the locations of the CHM files.

Normally, CHW files are not compressed, so they're typically rather large, but some programs do support compressing them to a much smaller file size.

How To Open an CHW File

If you're authoring Windows help files, FAR HTML will open CHW files for editing. This is done through the Authoring > Help File Explorer... menu. This program can also compress the CHW down to a smaller file size.

If you just have a CHM file and need to open it to read the help documents, you should be able to use a web browser like Firefox or Safari. If that doesn't work, other programs that can open CHM files include xCHM, WinCHM, PowerCHM, ChmDecompiler, Help Explorer Viewer, and ChmSee.

Tip: Don't confuse files with the .CHW or .CHM extension with ones that have a .CHA, .CHN, .CHX (AutoCAD Standards Check), or .CHD (MAME Hard Disk Image) file extension.

Those files don't open with the same programs as these help files even though they may appear similar.

If you happen to have a CHW file that isn't a Compiled Help Index file, which is possible, then it's unlikely that any of the programs mentioned here can open it. The best thing to do in that situation is to open the CHW file as a text file using Notepad++.

You can sometimes pull some key text out of the file that can help you determine what type of file it is (audio, document, image, etc.) or even what program was used to create it, which can help you research how to open that specific CHW file.

If you find that an application on your PC does try to open the CHW file but it's the wrong application or if you would rather have another installed program open CHW files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert a CHW File

If a CHW file can be converted to another format, it's probably possible with the FAR HTML program mentioned above, but I don't know of any sort of dedicated file conversion tool that can do it. You might normally use a document converter to convert file types like CHW, but this format isn't really the same as other document formats like PDF, DOCX, etc.

However, if you're wanting to convert a CHM file instead (a Compiled HTML Help file), like to PDF, EPUB, TXT, or other text formats, you can use the Zamzar program. Just upload the CHM file to that website and then choose which format you want to convert it to.

A similar website, Online-Convert.com, should convert CHM to HTML.

More Help With CHW Files

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the CHW file and I'll see what I can do to help.