I doubt that any paying user will be interacting with your system through a browser, but the browser-based demo could do a better job with status. You do show some activity updates, but it would be nice to know where in the overall process the task is. I was just about to bail when my one line C program finished. It took about 90 seconds. Yeah, I am impatient.

Your Lisp implementation would be interesting to me, but I don't know what the market size for a Lisp focused product would be. I actually don't know if the market size for C is great either. We did a huge toolchain refactor at DreamWorks a decade ago and there was a lot of C code, so maybe it would be relevant.