How to build a chat app like WhatsApp

WhatsApp, first released in 2009, quickly became the default setting for instant messaging globally. By 2014, it was so popular that Facebook acquired it. Core features of chat apps like WhatsApp include low latency messaging, channels and private messages, typing indicators, read receipts, emoji reactions, multimedia file sharing, targeted messages, push notifications, phone and video calls, compatibility, onboarding, and security. Challenges when building a chat app like WhatsApp include responding to sudden surges in usage, avoiding downtime and outages, achieving near-instant message delivery, delivering the right messages in the right order, and ensuring scalability, availability, and latency. Architecture considerations for building a chat app like WhatsApp involve choosing programming language, protocol, database, operating system, and virtual machine.