How are models rendered on the Sketchfab fronted

Hi everyone! I would love to know how 3d models are rendered on the Sketchfab frontend. I did some research and all I could find is how to use their Skechfab viewer API. The video by Sketchfab explains how to use the API in your own website as it references models from Sketchfab (Basically how APIs work). And it doesn’t explain how they are rendered.
Can someone kindly explain if the models are rendered on a dedicated GPU on the cloud or entirely rendered on the browser probably using Web GL.