Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.

Golden - Mapping all human knowledge

Encyclopædia Britannica - Explore the fact-checked online encyclopedia from Encyclopaedia Britannica with hundreds of thousands of objective articles, biographies, videos, and images from experts.

Sutle - Save and organize resources into a directed learning path.

Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!

Self-Defined - A modern dictionary about us.