New ask Hacker News story: Ask HN: What is the most cost-efficient COMPLEX web app you have seen?

Ask HN: What is the most cost-efficient COMPLEX web app you have seen?
3 by mrwnmonm | 0 comments on Hacker News.
I am looking for stories basically. So please don't start a philosophical fight over the definition of "complex" for example. And it doesn't matter if you created the architecture of that web app or someone else, please share it. I guess most people would be interseted in architectures that use cloud services, because not everyone can run their own servers or manage everything on their own. Thanks