Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.
Wondershare PDFelement - All-in-one PDF editor
Dr.Explain - Dr.Explain software is a help file authoring tool.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
CHM Editor - Best solution to edit CHM files