A simple one to start off. A program that was created so people can read Wikipedia if their Internet connection is down, or if access was blocked for some reason. Later extended to support other content, like old books that are out of copyright, docs for programming languages and the ArchWiki.

It gets the job done, even if the interface isn't the clearest. As far as I can tell it doesn't support any auto-updating, so it seems you do have to download a whole new version of each site when you want new stuff.

Have you used Kiwix? What do you think?