High-Level Design Problems
📚 New to system design? Start with the HLD Fundamentals — covers CAP, caching, sharding, queues, and estimation.
System design interview problems covering distributed architectures, databases, caching, messaging, and real-time systems. Each design includes diagrams, technology choices, deep dives, and trade-offs.
🟢 Beginner
| # | Problem | Key Topics |
|---|---|---|
| 1 | 🅿️ Parking Lot (LLD/HLD hybrid) | OOP, Strategy pattern, composition |
| 2 | 🏆 Real-Time Leaderboard | Redis sorted sets, top-N queries |
| 3 | 🚦 Rate Limiter | Token bucket, sliding window, Redis Lua |
🟡 Intermediate
| # | Problem | Key Topics |
|---|---|---|
| 4 | 🔗 URL Shortener | Base62, Snowflake ID, CDN caching, analytics |
| 5 | 🐦 Twitter / Social Feed | Fan-out on write vs read, timeline caching |
| 6 | 💬 Chat System (WhatsApp) | WebSocket, offline delivery, Cassandra |
| 7 | 🔔 Notification System | Multi-channel, Kafka, template service, engagement |
🔴 Advanced
| # | Problem | Key Topics |
|---|---|---|
| 8 | ⏰ Distributed Job Scheduler | Redis ZSET, leader election, retries, DLQ |
| 9 | ⏱️ Delayed Trigger Service | SQS + Cassandra, timing wheel, circuit breaker |
| 10 | 💰 Digital Wallet (PhonePe) | Double-entry ledger, idempotency, reconciliation |
| 11 | 🍔 Food Delivery (Zomato) | Elasticsearch, Redis Geo, dispatch, live tracking |
More designs coming every week. Drop a request in the comments below 👇
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