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System design

Microsoft system design

6 system design prompts sourced from real Microsoft loops. Each one ships with scale targets, evaluation rubrics, and a reference architecture diagram.

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senior System design

Design a real-time chat / messenger

Design a 1:1 and group chat service with delivery receipts, presence, and offline message delivery. Messages must arrive in-order and survive disconnects.

Scale targets

Users: 800M MAUQPS: 60M msgs/sec peakLatency: <200ms p99 deliveryStorage: ~100PB messages

Key areas

WebSocket gateway + sticky sessionsMessage ordering + idempotencyPresence + typing indicatorsPush notifications for offline usersEnd-to-end encryption boundaries

Reference diagram

Read-only — use it after attempting the prompt yourself.