About HTML Help .CHM File Format

The standard CHM file viewer on Windows

The standard viewer program allows you to open a .CHM file on any Windows computer, which makes the HTML Help format a versatile tool to distribute help files or other kind of documentation.

Below is a screenshot of a help file opened in the CHM viewer on Windows:

Thanks to the built-in navigation page with Table of Contents, alphabetical Index, and full-text Search capability, the CHM viewer program provides powerful tools for easy navigation through the entire help file, which is important for the end-user.

HTML Help (.CHM) and Context-Sensitive Help

As a help format developed for use in desktop applications, CHM allows the developer to provide Context-sensitive Help by using the HTML Help API calls directly, or by using an interface provided by many IDEs including Microsoft .NET and Embarcadero Delphi. You can view this article which explains how you can integrate a CHM help file with an application.

Currently we have code samples on integration of a .CHM file with a .NET application written on C# or VB.NET. Also you will find code samples for Delphi and VBA applications that can be used by Excel or MS Access developers who need to add CHM support to their apps.

Distribution of a CHM File

After you have compiled your help project into a single .CHM file or HMTL Help system, in most cases this is the only file that you need to distribute the entire help system to your users. This is possible since the CHM format stores all the data including content of help topics, Table of Contents, Index, and graphics images in a single file.

At the same time, it should be pointed out that if you use video in your CHM file, you may also need to distribute these video files together with the CHM file. Usually the video formats which are not embedded into the CHM are as follows: AVI, WMV, and MPG, which should be described in the help documentation for your help authoring tool.

HTML Help Portability

Although HTML Help CHM was developed for use in Windows, there are also third party document viewer applications that allow the user to open CHM files on different platforms including Linux-based systems.

Alternative Usage of CHM Files

Since an HTML Help system can contain a big number of linked HTML files within a single file with the .CHM extension, and also due to its portability, the HTML Help CHM file format is often used for distribution of many kinds of documentation and e-books, which are not limited to help files for software.

In other words, if you need to organize a bunch of articles into a single help system with a Table of Contents and Search capabilities, you can also consider creating a CHM file by using our instruction.

Known CHM file issues

If you are experiencing an issue with a CHM file you have just created or downloaded, you can refer to the following links.

Probably you will find a quick solution for the problems with your HTML Help (CHM) file.

• Why my CHM help file is not displayed?
• Search does not work in my CHM file