What is a .CHM file?
CHM is Microsoft’s Compiled HTML Help format, the help files of classic Windows software.
- Did you know
- CHM packs a help system - pages, images and an index - into one searchable file.
- CHM was introduced by Microsoft as the successor to the older WinHelp (.hlp) system, building help pages from a subset of HTML.
- Internally the format is called ITSF, for “Info-Tech Storage Format”, and it packs its pages together using LZX compression.
- What Analyser reads
- Open documents, ebooks and publishing files beyond Office: comic books (CBZ/CBT with ComicInfo + first-page preview; CBR/CB7 identified), Microsoft XPS, FictionBook FB3, iBooks, Scrivener, Visio VSDX, R Markdown/Quarto, RTFD, WARC/MAFF web archives, TeX DVI, legacy Hangul HWP, and WordPerfect/QuarkXPress/PageMaker identification.
- Depth of analysis
- .CHM is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .CHM file
- Drag a .CHM file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.