When Facebook acquired Instagram, the app had 30M users and was built by just 6 engineers. WhatsApp was rumored to have 35 engineers and 450M users. The high productivity per engineer and focus on application code, and not infrastructure or tooling, helped these teams stay lean. Dubsmash, a wildly popular mobile app, that lets you share and mash up famous quotes with fun videos, now has over 200 million users. Find out how they did it with just 3 engineers 😱.