Photo Sphere Viewer is pure JS and based on Three.js, allowing very good performances on WebGL enabled systems (most recent browsers) and reasonably good performances on other systems supporting HTML Canvas. Works with touch screens.
Supported projections: equirectangular
License: MIT License
Distribution Method: Downloadable Library
Price: free
Forked from the Photo Sphere Viewer by Jérémy Heleine to "provide a better JS architecture and a bunch of new features."