Design questions

 1. Design a Rate Limiter Every company covered this.

Know: Sliding window algorithms, Redis, race condition handling, token bucket vs. leaky bucket models.

2. Design a Chat Application A WhatsApp-style typing indicator alone can drive a 45-minute discussion.

Know: WebSockets, Redis Pub/Sub, message queues, offline message delivery.

3. Design a URL Shortener Appears straightforward. Becomes complex quickly.

Know: Base62 encoding, collision resolution, analytics tracking, Redis-based caching.

4. Design a Notification System

Know: Push vs. pull architecture, Kafka for asynchronous delivery, retry mechanisms, user preference management.

5. Design a Payment System JPMorgan asked this. So did multiple others.

Know: Idempotency keys, Saga pattern, ACID transactions vs. eventual consistency.

6. Design an API Rate Limiter Different from #1. This focuses on distributed system design.

Know: Token bucket algorithms, Redis INCR, Lua scripting, multi-node coordination.

7. Design a Video Streaming Platform

Know: CDN architecture, chunked uploads, adaptive bitrate streaming, large-scale storage systems.

8. Design a Ride-Hailing Application

Know: Real-time location tracking, matching algorithms, surge pricing strategies, live event processing.

9. Design an E-commerce Checkout System

Know: Inventory reservation, flash-sale scalability, payment retry workflows, order state management.

10. Design a Search Autocomplete System

Know: Trie data structures, frequency-based ranking, result caching, sub-100ms latency optimization.