zTree (Zurich Toolbox for Readymade Economic Experiments) allows the creation and running of economic experiments over a network, without any programming knowledge. Features include data saving, time display, profit calculation and tools for screen layout. A number of games and auctions are available for free download. It can be used for a wide range of possible experiments such as public good experiments, structured bargaining experiments or markets - including double auctions and Dutch auctions. Users need to sign a license agreement to use the software.