Social & Feed
Design a Chat System (WhatsApp / Messenger - Focus on WebSockets)
A real-time messaging platform maintaining persistent WebSocket connections, guaranteeing message delivery order and offline sync.
Open and Simulate this Architecture in InfraDraftCore Architectural Components
WebSocket Connection Gateway
Holds millions of stateful, long-lived client connections.
Message Store
Durable, per-conversation ordered log of every message sent.
Presence Service
Tracks online/offline/typing status and broadcasts changes to relevant peers.
Message Delivery/Ack Tracker
Sent/delivered/read receipt state machine per message per recipient.
Push Notification Service
Wakes a recipient's device when they're not actively connected.
Group Chat Membership Service
Manages who's in a group and fans messages out to all current members.
Media Attachment Storage & CDN
Handles images/video/voice notes off the hot messaging path.
End-to-End Encryption Key Exchange
Establishes and rotates per-conversation keys the server itself can't read.