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HDX CHM
Not possible

Convert HDX to CHM

Can you convert HDX to CHM?
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Is it possible to convert HDX to CHM?
No - not a direct conversion.

HDX is a compiled binary index to an associated .HLP. It cannot be directly converted to CHM. Migrating old WinHelp content to CHM requires the source RTF/HPJ project files, not the compiled index.

No direct path
Also to CHM: HLP · ZHELP · GID

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Tested on macOS, Windows & Linux
Last verified Oct 2026

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Converting HDX to CHM

A .HDX file and a .CHM file hold different kinds of data, so there is no direct way to turn one into the other.

A full step-by-step guide for this conversion is on the way; the information above is drawn straight from our database.

About these formats

.HDX AutoCAD Help Index File (Delphi MultiHelp Index)

An HDX file is a binary index used by the old Windows Help (WinHelp) system. It appeared in AutoCAD (as ACAD.HDX) and in Borland/Embarcadero Delphi. There is no way to open it on Windows 10…

Open .HDX details →
.CHM Microsoft Compiled HTML Help file

A CHM file is a Microsoft Compiled HTML Help file - a single compressed bundle of HTML pages, images, and a searchable index, used for Windows software manuals and e-books. On Windows,…

Open .CHM details →