The image below is being generated by a very simple path tracer I wrote based on Peter Shirley's
Ray Tracing in One Weekend.
It is written in C++ and compiled to WebAssembly using emscripten.
You can modify the number of samples used to generate a pixel (more samples will result in
a better looking image) and the number of browser threads to use (more threads should result
in faster execution) and then re-render the image. Timing is displayed in the text box below
the image.