HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.

Alfred - Alfred is an award-winning app for macOS which boosts your efficiency with hotkeys, keywords, text expansion and more. Search your Mac and the web, and be more productive with custom actions to control your Mac.

ManualsLib - Just enter the keywords in the search field and find what you are looking for!

MacPlus Software - Useful Mac Applications, Utilities for Mac Desktop, etc.

Manuzoid - Repository that includes user manuals for various products

Lacona - Fast, simple, powerful keyboard-driven commands for Mac