What this is
A library of interactive simulations for introductory and intermediate physics, built for teaching. Several replace the Java simulations that no longer run in a browser; others cover topics that never had a good simulation.
Each simulation is one self-contained HTML file. The physics is in a few clearly named functions near the top of the script, so you can check the model, change a constant, or turn it into a different problem.
Use it, share it, improve it
Use any of these in a lesson, a course site, or a learning management system. Link to a simulation directly, or download the file and host it yourself; it keeps working without this site.
To report a problem or contribute a simulation, go to the repository on GitHub. A new simulation is one file in sims/ and one entry in sims.js.
Good simulations elsewhere
Some topics are already done well by others: Ray Optics Simulation for geometric optics, myPhysicsLab for mechanics with the equations shown, EMANIM for polarization and electromagnetic waves, and of course PhET. This library aims to fill the gaps around them, not to redo them.