System Design Use Cases
System Design Use Cases
Real-world system design case studies, each built to a single, strict framework: precise requirements → capacity estimation → high-level architecture → iterative refinement → deep dives (APIs, schema, data structures, algorithms) → interview tips, resiliency, and observability.
New designs follow the shared framework template (_TEMPLATE.md) in this folder.
URL Shortener
Key generation, base62, cache-aside redirects, bloom filters, analytics
Rate Limiter ServiceToken bucket & sliding window, Redis Lua atomicity, fail-open vs fail-closed
Real-Time LeaderboardRedis sorted sets, top-N & rank queries, tie-breaking, sharded scaling
Distributed CacheConsistent hashing, stampede prevention, hot-key replication, eviction
Typeahead / AutocompleteTrie with top-K per node, offline pipeline, trending updates, sharding
Notification SystemMulti-channel fan-out, DLQ retries, dedup, user preferences
Key-Value StoreConsistent hashing, quorum R/W, gossip failure detection, LSM storage
Distributed Message QueuePartitioned logs, consumer groups, ISR replication, exactly-once
Twitter Home TimelineFan-out on write vs read, hybrid for celebrities, ranking, media
Instagram / Photo SharingMedia pipeline, CDN delivery, hybrid feed fan-out, likes at scale
Web CrawlerURL frontier, bloom-filter dedup, politeness, distributed coordination
Search EngineInverted index, BM25, sharded query processing, link analysis
Uber / Ride-SharingGeospatial indexing, matching, trip tracking, surge, payments
WhatsApp / Chat SystemWebSockets at scale, message ordering, delivery receipts, E2E encryption
YouTube / Video StreamingTranscoding pipeline, adaptive bitrate (HLS/DASH), CDN, metadata
Google Maps / NavigationRoad-network graph, A* routing, map tiles, real-time traffic, ETA
Dropbox / Google DriveChunking, content-addressed dedup, delta sync, conflict resolution
Payment SystemIdempotency, double-entry ledger, saga/outbox, reconciliation