Another billion dollar open source company

There are lots of multi-billion dollar turnover companies that are based on open source - Google, Facebook, Twitter etc. - it's just that they don't make money off it directly.

Another company that is open source through and through has done rather well recently. Everyone and their dog must know by know that Instagram is being bought by Facebook for $1 billion, but less well known is the fact that the company is built entirely on open source.