How WhatsApp scaled to 1 billion users with only 50 engineers

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In 2016, WhatsApp reached more than a billion users. They managed to serve this scale with only 50 engineers. By @quastor.org. They had the following load stats: 42 billion messages sent daily, 1.6 billion pictures sent daily, 250 million videos sent daily.

Here’s a dive into the engineering culture and tech stack that made this possible. WhatsApp’s Engineering culture consists of 3 main principles:

  • Keep things small
  • Keep things simple
  • Have a single minded focus on the mission

WhatsApp consciously keeps the engineering staff small to only about 50 engineers. Individual engineering teams are also small, consisting of 1-3 engineers and teams are each given a great deal of autonomy. In terms of servers, WhatsApp prefers to use a smaller number of servers and vertically scale each server to the highest extent possible.

Their goal was previously to have 1 million users for every server (but that’s become more difficult as they’ve added more features to the app and as users are generating more activity on a per-user basis). Read the article in full to learn more details. Excellent read!

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Tags performance web-development programming app-development open-source