Real-time · 9 min · 2026-07-15
Building Real-time Chat with Socket.IO and Redis
Presence, fan-out and reconnect strategies that keep chat usable under load.
Real-time chat is less about the library and more about reconnect, presence and fan-out.
Redis helps when multiple Node processes must share socket state. Design for duplicate events and late joins. Persist only what product needs — ephemeral presence can die with the process cluster.
Always measure latency under concurrent sessions before calling it production-ready.