Where could I find information about the level of Go playing software? In particular, I am looking for commercial software.
Ideally, I'd like to find a live ranking, as obviously this field is evolving fast.
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Obviously, AlphaGo is the top AI now. Besides it, a simple way to find information about Computer Go Ranking would be to search for :
Computer go tournament
Here is a list of Go AI from wikipedia
There's a special website called Computer GO that registers past and future tournaments.
There's also a website for KGS Computer Tournaments
According to the KGS tournament, the actual ranking is :
As for commercial AIs, I don't think their level match the ones quoted here. It would require much hardware resources to run on a smartphone or a personnal computer.
Some of the strongest programs, like CrazyStone and Zen, have now reached the top 100 on KGS, their current KGS ranking is available on this page.
Sensei's library has a page dedicated to KGS bot rating, including highest rank, historical rating and current rating.
As of March 2016, CrazyStone and Zen19X are KGS 7d, Hira is KGS 5d. According to his author, CrazyStone has become considerably stronger thanks to deep learning.