Very interesting concept.
One question: the data that gets input (for example via file-input), does it stay local in the browser or is it (temporarily) uploaded somewhere?
Everything stays locally in the browser, nothing is uploaded.
Greate work! Does the WebWorker execution comes with any performance issues ?
Well yes. The biggest limitation is the max. string size. For passing the data to the WebWorker. But I was impressed by the browser speed for the raytracer example.