Design Swiggy's Real-Time Order Tracking System

Problem

Design the backend for Swiggy's live order tracking — where customers see the delivery agent's location update in real time on a map.

Requirements

Functional:

• Customer sees agent location update every 5 seconds
• ETA recalculation on each location update
• Agent app sends GPS coordinates
• Push notification on key milestones (order picked up, nearby)

Non-functional:

• 2M concurrent active orders at peak
• Location update latency < 3s end-to-end
• 99.9% uptime

Discussion points

1. Agent → server: HTTP polling vs WebSocket vs MQTT
2. Server → customer: Server-Sent Events vs WebSocket
3. Location storage: time-series DB vs Redis sorted set
4. ETA model: static map + ML delta correction
5. Geo-fence triggers for push notifications