Panda Sensei (パンダ先生) is a tsumego solving AI developed in Japan.
The AI is offered as a subscription service on the Pandanet (Japanese side of IGS) from 2003. It costs JPY 500/month (JPY 1,000/month together with other learning resources). This patented service is even used by professionals to check the soundness of their compositions.
You can download a mobile app for the service at IGS (English page).
Panda Sensei Challenge Match has been held as a side event of Pair Go World Cup. The AI and human players compete speed and accuracy in solving tsumego problems. Panda Sensei have beaten many professional pairs. The following links include many photos and the problems used: