[tetraodonpuffer]

I think that would be

https://icga.leidenuniv.nl/

I can't find the claimed ELO for Jonny (current champ) but Junior (previous champ) is listed at 3200+, Magnus' top rating, the highest ELO rating ever, is 2882 for reference

[bluecalm]

This is not a serious competiton. For serious stuff, see for example:

1)http://tcec.chessdom.com/

2)http://www.computerchess.org.uk/ccrl/4040/

There is a lot of politics in chess programming but the bottom line is that Komodo is currently the strongest program followed by Stockfish (which is distributed under GPL).