CHM

CHM (Compiled HTML Help), AKA Microsoft Help 1, is a Microsoft format for help files. While it is proprietary, it has been reverse engineered, and many software applications can read it.

It is a compressed binary file format, including content in HTML as well as other related data.

Microsoft Help 2 was intended as a successor, but never saw much use.

Format description

 * chmspec

Software

 * chmdeco
 * KchmViewer
 * libmspack
 * chmlib
 * CHM Tools
 * 7-Zip
 * archmage

Sample files

 * https://telparia.com/fileFormatSamples/document/chm/

Links and references

 * Wikipedia article
 * Ancient help-file format carries new CryptoWall attacks into PCs