Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!
Miraheze - Miraheze is a wiki farm (hosts wikis) for free and with no ads, it also provides custom domains...
XOWA - The free, open-source, offline wiki application
Fandom - The entertainment site where fans come first.
Evopedia - Evopedia is an offline Wikipedia viewer. Features: no Internet connection needed
Wikiful - Wikiful is an online platform that makes it easy to build and share a wiki.