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!
Lacona - Fast, simple, powerful keyboard-driven commands for Mac
Manuzoid - Repository that includes user manuals for various products
MacPlus Software - Useful Mac Applications, Utilities for Mac Desktop, etc.
ManualAgent - Manuals and guides