Doxygen - Generate documentation from source code
ManualsLib - Just enter the keywords in the search field and find what you are looking for!
DocFX - A documentation generation tool for API reference and Markdown files!
Internet Archive Manual Library - Internet Archive Manual Library is your go-to source for viewing the big collection of datasheets, instructions, and guides written for a wide range of products.
NDoc - NDoc generates class library documentation from .
ManualAgent - Manuals and guides