This is FEN2Wikipedia, a simple tool that takes Chess positions described using the Forsyth-Edwards Notation (FEN) format, and converts them into the Wikipedia format for chess diagrams (using the "Chess diagram" template).
Enter the data below (at least the FEN value) and press the "Generate Wikipedia Text Result (below)" button. The Wikipedia format will be displayed below, which you can then cut and paste into Wikipedia.
Wikimedia commons has more information on the Wikipedia standard "chess diagram" template. This form takes normal FEN (e.g., "N" is white knight and "n" is black knight), as well as "x" for a cross, "o" for a circle on an empty squre, and the Capablanca chess symbols "a" for archbishop and "c" for chancelor. It uses two characters for a position, not one (the second character shows the side of the piece/pawn); this means that the data will work correctly on case-insensitive systems. Wikipedia itself works correctly with case-sensitive data, but by storing data this way, the data will work correctly even on case-insensitive (some might say case-corrupting) systems. In other words, by doing things this way, the data is more portable.
You can get the latest version of FEN2Wikipedia from http://www.dwheeler.com/misc/fen2wikipedia.html.
FEN2Wikipedia is open source software / free software (OSS/FS). That means that you can freely give it to anyone, and you can modify and redistribute modified versions of it to whoever you wish. FEN2Wikipedia is Copyright (C) 2005 David A. Wheeler, and comes with ABSOLUTELY NO WARRANTY. FEN2Wikipedia is licensed under the GNU General Public License (GPL), version 2 or later.