Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
Untools - Hand-picked tools for better thinking
Encyclopædia Britannica - Explore the fact-checked online encyclopedia from Encyclopaedia Britannica with hundreds of thousands of objective articles, biographies, videos, and images from experts.
Super Thinking - The big book of mental models
Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
Notionery - Mental models made for Notion