Pattern series
Sharding and Hot-Key Mitigation
16 System Design questions share this exact tag. Use the closely related series below for a fuller drill.
- 01Free guide
Ad Click Aggregator
Design an ad click aggregation system that ingests millions of click events per second and serves near-real-time plus historical aggregate metrics to...
Meta - 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
Facebook Post Search
Design search over a social feed — let users find posts by keyword in near real time while respecting each post’s privacy/visibility settings.
Meta - 04Preview
Game Leaderboard
Design a real-time game leaderboard that ranks millions of players by score, supports regional and time-windowed boards, and serves both top-N and a g...
Strava - 05Preview
Metric Monitoring and Alerting
Design the metrics pipeline behind a monitoring platform — the path from an SDK on thousands of hosts emitting numeric measurements, through streaming...
Uber - 06Free guide
Top K Songs (Spotify)
Design Spotify's Top-K most-played songs feature — compute top charts over sliding time windows at listening-event scale.
Spotify / Meta - 07Free guide
Uber (Ride Hailing)
Design Uber — a ride-hailing platform matching riders to nearby drivers in real time, with live location tracking, pricing, and trip lifecycle managem...
Uber - 08Free guide
Web Crawler
Design a web-scale crawler that politely fetches and indexes billions of pages, deduplicates content, and keeps the corpus fresh.
Google - 09Free guide
- 10Preview
- 11Preview
Vector Database
Design the storage and query engine of a vector database that indexes billions of embeddings for approximate nearest-neighbor search.
Meta (Faiss) - 12Preview
Distributed Key-Value Store
Design a Dynamo-style highly available key-value store: partition keys across nodes with consistent hashing, replicate each key to N nodes, and let ev...
Practice bank - 13Preview
Distributed Cache
Design a distributed in-memory cache service at Redis/Memcached scale that serves roughly 1M QPS at p99 under 5ms.
Meta - 14Preview
Distributed Message Queue
Design a Kafka-style durable, partitioned log broker that ingests high-throughput event streams.
Apache Kafka (LinkedIn) - 15Preview
Food Delivery Marketplace
Design a DoorDash-style food delivery marketplace connecting consumers, Dashers, and merchants.
Uber - 16Preview
Live Comments
Design a live comments system that fans out comments from one live event to millions of concurrent viewers in real time.
Meta