For creating online private wikis for free, you can use software called Zim. It is a desktop application that enables you to create and organize personal wikis. We have mentioned its features in detail which you can check out in this guide. Apart from that, PmWiki is one of the best free open source wiki software that you can use for collaboratively editing, creating, and maintaining web pages. Besides that, MediaWiki and DokuWiki are some other open source wiki software that are really good. These wiki software provide simple editing features, various security functions, multiple export options, customizable skins, and many more handy features.