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A great wiki engine used on Wikidot.com is now free software are Wikidot Inc owners: Pieter Hintjens and Piotr FrÄ…ckowiak, release the code on AGPLv3 license just today. This is great news for the Internet as Wikidot is one of the most advanced wiki engines out there, leaving MediaWiki and TWiki far behind.

Choose two GNU/Linux or BSD flavors and see how they compare in features and supported software/hardware. This may help you select the right operating system for your needs.