z-Tree is a widely used software package for developing and carrying out economic experiments. The language used to define the experiments is simple and compact, meaning that experiments can be developed quickly, and programming experience is not necessary, though useful.
z-Tree is flexible both with respect to the logic of interaction and the visual representation, allowing the simple programming of normal form games, extensive form games, double auctions, or clock auctions, for example. We began the development of the software in 1998, and have continually added new features.
The z-Tree software is implemented as a client-server application with a server application for the experimenter, called z-Tree, and a client application for the subjects, called z-Leaf.
The applications are programmed in C++ (Visual C++ 2022, MFC) and run on all recent released x86 32 bit and 64 bit versions of Windows, starting with Windows 7.
To run z-Tree on a Mac, you need a virtual machine like VirtualBox, VMware or Parallels. On Linux you may use wine.
The current version 5.1.13 has been released on February 20, 2024.
The program can be licensed free of charge. Please note that z-Tree may only be used for academic purposes. If you are not part of an academic institution but want to use z-Tree for research purposes, please contact us
When you report results of experiments conducted with z-Tree, the licence requires that you mention it's use in the publication and cite the article published in Experimental Economics.