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

Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.

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

Anchor CMS - Free and lightweight blogging system

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

Textpattern - Textpattern is an elegant content management system that is free, open source software.