Kramer M., DP ITS, DTM, BN wrote:

Dear mediawiki, I investigate mediwiki as a mean of communikation inside my company. Would I have to pay licence fees?

MediaWiki is free for any use, commercial or not. The license covers redistribution and distribution of derivative works; see the file COPYING in the distribution for the full license terms (GNU General Public License, version 2.0)

In brief: if you redistribute MediaWiki itself you must offer the source code as well (this is easy; you have to go out of your way to distribute PHP programs without source code). If you modify MediaWiki and distribute the modified version, you again must offer the complete source code for your modified version. If you are simply running it on your servers, and not distributing copies of the program, then you can modify it as much as you like without having to show anyone your work.

-- brion vibber (brion @ pobox.com)