Learn to design scalable, reliable systems that handle millions of users. System design interviews test your ability to architect real-world applications, considering tradeoffs, scalability, and best practices.
Core Topics:
Scalability: Load balancing, horizontal vs vertical scaling
Storage: Databases (SQL vs NoSQL), caching (Redis, Memcached)
Reliability: Replication, failover, disaster recovery
Performance: CDNs, caching strategies, database indexing
Common Design Questions:
Design URL shortener (bit.ly)
Design rate limiter
Design Twitter/Instagram feed
Design messaging system (WhatsApp)
Design file storage (Dropbox)
Interview Level: Senior engineers (L5+) at FAANG companies. Requires 3-5+ years experience to tackle effectively.
Preparation: Study system design patterns, understand distributed systems fundamentals, and practice mock interviews.
6 min read What is a Distributed Configuration Service? A configuration service manages application settings, feature flags, and operational parameters across a distributed […] Read article
6 min read Requirements Producers enqueue tasks; workers process them asynchronously At-least-once delivery: tasks must not be lost on worker crash Retry with Read article
6 min read What is A/B Testing? A/B testing (controlled experimentation) randomly assigns users to experimental variants and measures which variant produces better Read article
6 min read Requirements Detect fraudulent transactions in real time (<200ms per transaction decision) Flag suspicious user behavior: account takeover, card testing, synthetic Read article
6 min read Requirements Ingest billions of events per day (page views, clicks, transactions, errors) Support real-time dashboards with <10 second lag Support Read article
6 min read Requirements Record every ad click event (ad_id, user_id, timestamp, ip, device_type) Query click counts per ad for any time range Read article
6 min read What an API Gateway Does An API gateway is the single entry point for all client requests to a microservices Read article
5 min read Requirements Update a player score in real time Query the global top-100 leaderboard Query a player’s exact rank among all Read article
6 min read Why Distributed Locks? In a distributed system, multiple servers run the same code concurrently. A distributed lock ensures only one Read article
6 min read Requirements Users can browse events, select seats from a seat map, reserve seats, and complete payment Prevent double-booking: no two Read article
6 min read Requirements One-on-one messaging and group chats (up to 500 members) Real-time message delivery (< 100ms), offline message storage, read receipts Read article
6 min read What a CDN Does A Content Delivery Network caches content at edge Points of Presence (PoPs) geographically close to users, Read article
6 min read Upload Pipeline Raw video upload → object storage (S3 raw bucket) → message published to transcoding queue (SQS/Kafka) → transcoding Read article
6 min read Requirements Design a file storage system like Google Drive or Dropbox supporting: Upload and download files up to 50 GB Read article
6 min read Core Services A ride-sharing platform like Uber or Lyft decomposes into focused microservices: Location Service: ingests driver GPS pings, maintains Read article
