I’ve known Zendesk pretty much since its inception. In fact, I was the first person to write about the company, soon after they launched eight years ago or so. (Disclosure: For a very short period some years ago I consulted to Zendesk around their communications strategy). Back then it was just the three co-founders and lovable sidekick Michael Folmer Hansen (not to mention his alter ego, Jennifer Hansen, a fictitious character that now, as then, greets new customers via email).
Roll on a few years and not only has the company moved location (from Copenhagen to Boston first and then on to San Francisco) but it has grown and is now a publicly listed company.