What is .HXK file extension?
File used by Microsoft Help 2.x projects; specifies information about how a help index is organized; often used for keyword, context-sensitive, and other help indexes defined in the .HXS help documentation bundle.
NOTE: Older versions of Visual Studio, including 2005 and 2008, used Microsoft Help 2.x as the standard help format. However, Visual Studio 2010 and later no longer support Microsoft Help 2.x.
You can see a list of software programs here on www.easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.