Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
Stylebot - Change the appearance of websites instantly. Preview and install styles created by other users on stylebot.me
Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
FreeStylerWs - Styles and skins for all popular sites in the web
Oppia - Oppia is a free, open-source learning platform.
Amino Editor - Amino is a Chrome browser extension for customizing web page presentation with user CSS.