Designing WhatsApp's Typing Indicator: The Question That Tests Your Real-Time Skills

Book: System Design Pocket Guide: Interviews Also by me: Event-Driven Architecture Pocket Guide My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub Picture walking into a system design loop at a major messaging company. The interviewer skips the usual "design a chat app" prompt and asks something narrower: design the three little dots. The typing indicator. The small grey ellipsis that appears under your contact's