System Design of a Text-to-Image Product at Scale

1. The Question

"We run a consumer text-to-image product. Users type a prompt and get four images back. There is a free tier and a paid tier. We generate about 2 million images a day, and that number is growing. Design it, and I care about the bill."

Stop. Run it yourself against the clock before reading on. And notice the last five words. The interviewer just told you where the points are.