.HLP File Extension
What is an HLP file?
An HLP file contains help documentation used by Windows Help, a help program included with previous versions of Windows. Typically, the documentation helps users use a specific Windows app or feature. HLP files are now uncommon, since current versions of Windows do not include Windows Help.
Starting with Windows 3.1, Windows included an online help program named Windows Help (winhelp.exe or winhlp32.exe). Windows XP was the last version of Windows to include the program by default. The program was available for download and use with Windows Vista, 7, 8, and 8.1, but officially discontinued as of Windows 10 and Windows Server 2012.
Windows Help used HLP files to show help documentation to users. The HLP files include not only documentation, but also indexes allowing users to navigate documentation more easily. Developers compiled HLP files using Microsoft Help Workshop (HCW.exe).
NOTE: HLP files created for older versions of Windows may not be compatible with newer versions of Windows.
How to open an HLP file
You can open an HLP file with Microsoft Help Viewer (Windows), Adobe RoboHelp (Windows, Mac), or Help Explorer Viewer (Windows). Help Viewer is a Visual Studio add-on; it is not the same program as Windows Help.
How to convert an HLP file
You can use Adobe RoboHelp (Windows, Mac) or YpgSoft Windows HLP To RTF (Windows) to convert HLP files to other formats.