Google and Facebook both don't use git. Google uses a proprietary, perforce-esque system with multiple frontends, and Facebook uses Mercurial. Among startups,

Google and Facebook both don't use git. Google uses a proprietary, perforce-esque system with multiple frontends, and Facebook uses Mercurial. Among startups, I'm sure git holds a near monopoly, but if you move into other parts of the industry, that monopoly loosens.