What is a CHW file?
A .CHW file is a Compiled Help Index File created by Microsoft. It stores an index of keywords for combined HTML Help systems. When developers merge multiple .CHM (Compiled HTML Help) files into a single system, the software generates a .CHW file. This file speeds up the search and index functions.
How to open CHW files?
The Windows operating system uses .CHW files automatically when you open a linked .CHM file using the Microsoft HTML Help Executable. You do not usually open a .CHW file manually. If you are unsure about the contents, viewer.online/chw analyzes .CHW files to identify their exact format and creator software, shows which programs can open the file, and usually previews it.
Conversion and Best Practices
Because a .CHW file only contains index data, converting it is rarely necessary for standard use. If you need to extract the raw index text, you can use specialized extraction tools or recommend file conversion to sensible target formats like .TXT or .HTML on convert.guru. Keep the .CHW file in the same folder as its corresponding .CHM files to ensure the help system works correctly. If you delete a .CHW file, Windows will recreate it automatically to repair corrupted indexes.
Summary
viewer.online/chw directly opens and previews .CHW files in the browser, eliminating the need to install software or troubleshoot compatibility issues.