Joist is the main framework for PhET Interactive Simulations. Joist creates and displays the simulation content, home screen, navigation bar, About dialog, enables switching between screens, and other framework-related features.

By PhET Interactive Simulations http://phet.colorado.edu/

The PhET Development Overview is the most complete guide to PhET Simulation Development. This guide includes how to obtain simulation code and its dependencies, notes about architecture & design, how to test and build the sims, as well as other important information.

See the license