Pattern series
Persistent Connection Management
9 System Design questions share this exact tag. Use the closely related series below for a fuller drill.
- 01Preview
Chat App
Design the client-side architecture of a WhatsApp-style mobile messenger — connection handling, message state, offline storage, and encryption all hav...
Discord - 02Preview
Chat Service
Design the backend infrastructure behind a chat product — stateful connection servers, message storage, and group fan-out — for hundreds of millions o...
Discord - 03Preview
Collaborative Shopping
Design a collaborative shopping experience where multiple people share a single cart in real time, add and remove items concurrently, and one designat...
Practice bank - 04Free guide
Facebook Messenger
Design Facebook Messenger — a real-time chat system delivering messages with low latency, ordering guarantees, and multi-device sync at massive scale.
Meta - 05Preview
Google Doc
Design Google Docs’ real-time collaborative editing — multiple users typing in the same document simultaneously and seeing each other’s edits converge...
Google - 06Preview
IoT Device Platform
Design a platform managing ~10 million connected devices over MQTT: connection lifecycle and disconnect detection, telemetry ingest at fleet scale, an...
Practice bank - 07Preview
Real-time Voice AI Agent
Design a real-time voice AI agent platform for phone support and voice assistants: the complete loop from the user speaking to the agent speaking back...
Practice bank - 08Preview
Real-time Multiplayer Game
Design an authoritative server for a real-time multiplayer game.
Riot Games - 09Preview
Live Comments
Design a live comments system that fans out comments from one live event to millions of concurrent viewers in real time.
Meta