What are some alternatives?
Fandom - Anyone can create a wiki!
Infogalactic - The planetary knowledge core
TiddlyWiki - TiddlyWiki — a non-linear personal web notebook
Oppia - Oppia is a free, open-source learning platform.
Miraheze - Miraheze is a wiki farm (hosts wikis) for free and with no ads, it also provides custom domains...
Everipedia - The world's largest english encyclopedia