.chm
Documents · application/vnd.ms-htmlhelp
Opens with
Text, tables and slides. Many have open standards so they can be read outside the program that made them.
| MIME type | application/vnd.ms-htmlhelp |
|---|---|
| Category | Documents |
| Opens in a browser | No |
| Plain text | No |
| Registered type | Yes |
How to read this
- An extension is a label, not the contents. Rename a file to .png and if the bytes inside are JPEG, it is still a JPEG.
- A MIME type is how the internet names a file kind. Browsers look at that value, not the extension, to decide whether to display or download.
- A MIME type starting with x- was never registered as a standard. Plenty are in wide use, but they are not official names.
- Video extensions name a container. The same .mp4 may play on one device and not another, depending on the codec inside.
Frequently asked questions
Q. What is a .chm file?
It belongs to the documents category and its MIME type is application/vnd.ms-htmlhelp. The contents are binary, so opening it in a text editor shows garbage.
Q. What opens a .chm file?
HTML Help, Calibre, xCHM all handle it. In a browser it does not display — the browser downloads it instead.
Q. What is the MIME type of .chm?
application/vnd.ms-htmlhelp. The first half, application, names the broad kind; the second half, vnd.ms-htmlhelp, names the exact format. It is a registered standard name.
Q. Can I convert a .chm file to another format?
Yes — open it and re-save through a converter. Renaming alone changes only the label; the bytes stay put, and programs that check the real format may refuse to open it.
Q. My .chm file will not open.
First check that HTML Help is installed. If it still fails, the download may have been cut short, or the file may only be named .chm while holding a different format inside.