Microsoft Compressed HTML Help is a proprietary format for online help files. They have a set of web pages written in a subset of HTML and a hyperlinked table of contents. CHM format is optimized for read, as files are heavily indexed. All files are compressed together with an LZX . Most CHM browsers display a table of contents on the left.
A CHM help file has a ".chm" or ".CHM" suffix. The file starts with bytes "ITSF" (in ASCII), for "InfoTech Storage Format".
There are some open source tools which can read and explore these files (see for example xCHM or GnoCHM), but they lack various features of the Microsoft Windows tools.
HTML Help files are made with applications such as PowerCHM or HTML Help Workshop.
For more information go to HTML Help Web Page on MSDN.
Extracting to HTML
On Windows, a CHM help file can be extracted to plain HTML with the command:
hh.exe -decompile folder chm
or by using HTML Help Workshop.
On Linux, a CHM file is extracted to plain HTML with
$ sudo apt-get install chmlib-bin $ extract_chmLib tero.chm tero/
External links
- Open source
- Non-free tools
- Additional Information and Tools
- The Helpware Group — Tips, Tricks, various free and non-free HTML Help tools
- Help File Consultants and Outsourcing
- Help File Solutions - Create CHM help files from Word or Framemaker files
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