How Does WhatsApp Work? Architecture Deep Dive
Blog post from Stream
WhatsApp, developed by Meta, is a globally dominant messaging app with over 3 billion users monthly, although its adoption is relatively limited in the US. It serves as a vital communication tool in regions like Brazil, India, and Europe, supporting text, voice, and video communications, all secured with end-to-end encryption. WhatsApp's infrastructure is designed for massive scale and reliability, handling over 140 billion messages daily with 99.99% uptime, utilizing technologies like FunXMPP for efficient data transmission and Erlang/OTP for robust concurrency and fault tolerance. FunXMPP compresses messages significantly, making WhatsApp viable even on slow networks, while Erlang/OTP ensures seamless operation by managing millions of lightweight processes and maintaining system stability. The app's architecture, centered around minimizing complexity and maximizing efficiency, allows it to operate effectively with a relatively small engineering team, demonstrating the power of using established, reliable technologies to build scalable systems.