Yes, WhatsApp. Of course. The only successful platform using Erlang (although to what extent, not quite clear). What's also not clear is whether that platform would have been more successful or easier to design with another technology. We'll never know.

What we know is that, like I said, the number of Java EE projects out there absolutely dwarfs the number of Erlang projects. That was my one and only point. I never compared the quality of these two platforms, I just offered a simple mind share fact.