The vast majority of (web) startups leverage open source technology. Most use both an open source database as well as programming language(s). Beyond that, ma

The vast majority of (web) startups leverage open source technology. Most use both an open source database as well as programming language(s). Beyond that, many use an open source framework on top of their language of choice. Building around someone else's APIs isn't such a cardinal sin as you're implying. The big questions is what are you building? Owning and controlling your full stack is important if you're building something huge, but you can build something profitable leveraging someone else's APIs. There's a bias here towards building BIG businesses rather than lifestyle businesses, so advice about avoiding third-party APIs would come from that. If it works for the project you're doing, then do it. If not, then don't.