The codes are generated on their backend in a C program, but I don't see any reason why it couldn't be done in WASM.
Ultimately it should be made possible to do it locally. Current setting is low-quality and takes about 1-2 seconds. Mid-setting about 20 seconds and high about 20 minutes.
It's a front/back-end system. I'm currently running the backend on a c5a.xlarge instance.
Ah, I thought it's done client side. Never mind then.