App developers often makes their documentation available as help files through CHM files i.e Compiled HTML files than of  PDFs, which can be easily opened in any Windows operating system you’re using with built-in CHM Viewer (may be not sometimes in Windows 7 ), what about if you’re using Linux or Mac operating systems to view them you’ve to install separate programs, instead you can use ChmFox Firefox add-on which lets you open CHM files directly in Firefox browser.

view CHM files in Firefox

Using ChmFox in Firefox

Download and install ChmFox extension for Firefox and select CHM file via explorer by selecting Open File button from File Menu (just use Ctrl + O instead, easy). Or you can drag-n- drop CHM file onto Firefox address bar and press enter to open.

You can show/hide index sidebar and content with “Ctrl + M “ shortcut.

ChmFox works on Windows, Linux and Mac.