This applet allows to input (preferably completely closed) life & death problems or to have a random problem to be displayed, to have them analysed and to explore different variations interactively. Apart from life & death problems also ladder problems can be handled. The applet is based on the program GoTools.
In the last 5 years this free online service has solved over 100,000 Tsume Go problems. You can help to improve GoTools by donating money which will essentially be used to fund student projects.