PsychoPy

About

PsychoPy is free to download and run for in-lab studies, and its code is open source on GitHub. It offers a Builder interface for creating experiments without coding as well as a Coder option for writing custom code, and it is used in teaching, with textbooks, YouTube tutorials, and workshops available. The site describes precise graphics and timing, including hardware-accelerated graphics, built-in calibration tools, and stimulus updates on every screen refresh, along with support for button boxes, fMRI non-slip timing, and sending triggers to serial or parallel devices.

For online studies, PsychoPy has a JavaScript sister library, PsychoJS, which lets researchers create browser-based versions of experiments and host them on Pavlovia.org. Pavlovia is described as a secure server for hosting experiments, a library of open-access demos, and a tool for creating surveys, and the site notes that participants can be recruited through systems such as Sona, Prolific, or Mechanical Turk. Pavlovia licenses, consultancy, and workshops are cited as the revenue streams that support ongoing development by Open Science Tools.