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  • WhatsApp · System Design

WhatsApp

LearnViaNotes @learnvianotes· 1 min read

A global messaging platform with 2B users, 100B+ messages/day. Core challenges: message delivery guarantees, online presence, E2E encryption.

Requirements

Message Delivery Flow

Sender App → WebSocket Server → Message Service → Message Store (Cassandra)

x → x ↓ Presence Service → Recipient WebSocket / Push Notification

WebSockets for Real-Time

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