Wiki

Confluence has two main advantages: It's very fast to create/edit pages, and it has a hierarchiecal page tree to organize information logically.

Personal Information Manager

Very solid tool, enough power for my demands

Provides unlimited private wiki together with repo for free, and has clean and good-looking UI.

Scoold is a great Q&A / knowledge base platform for teams of all sizes. It enables efficient knowledge sharing based around questions, answers, comments and tags.