Our YC company (Heysan, W07) was very similar to WhatsApp except we decided to shim mobile web into the IM networks of that time. We were closing our doors as t

Our YC company (Heysan, W07) was very similar to WhatsApp except we decided to shim mobile web into the IM networks of that time. We were closing our doors as they were just getting going, and we really liked what we saw of them. At that time we had pretty much re-written everything to be erlang - it definitely makes writing IM software easy to reason about. Interoping with the IM networks was very graceful in erlang.