Files that contain the .chw file extension are normally associated with index files that are related to multiple associated CHM (compiled HTML help) file.
When a compiled HTML help file is created and the separate components (CHM files) are merged together, the CHW file is automatically created.
The CHW file contains the table of contents for the help file and the references to each CHM file that is listed within the help file table. Each time a new CHM file is added to the compiled help file list, the CHW is automatically updated.
The CHW file format is similar in nature to the GID file format.
Try a universal file viewer
File.org aims to be the go-to resource for file type- and related software information. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files.
If you have additional information about the CHW file format or software that uses files with the CHW suffix, please do get in touch - we would love hearing from you.