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.
Requirements Send transactional emails (password reset, order confirmation, notifications) and marketing emails (campaigns, newsletters) 100M emails/day, peak 10K/second during campaigns […]
What is a CI/CD Pipeline? CI (Continuous Integration): automatically build and test code on every commit. CD (Continuous Delivery/Deployment): automatically
What is a Secret Manager? A secret manager stores and distributes sensitive credentials (API keys, database passwords, TLS certificates, OAuth
What is a Log Aggregator? A log aggregator collects logs from distributed services, normalizes them, stores them for search, and
Why Rate Limiting? Rate limiting protects services from abuse, ensures fair usage, and prevents cascading failures from traffic spikes. Applied
What is a Webhook? A webhook is a user-defined HTTP callback. When an event occurs in a platform (payment succeeded,
Why Multi-Region? Single-region deployments fail entirely during a cloud provider AZ or region outage. Multi-region provides: (1) High availability —
Requirements Generate invoices for subscriptions and one-time purchases Support multiple billing cycles: monthly, annual, usage-based Apply discounts, taxes, and proration
Requirements Return top-k (k=10) query suggestions as a user types, within 100ms Suggestions ranked by search frequency or relevance score
Requirements Generate a personalized feed of posts ranked by relevance/recency for each user Supports follow relationships: see posts from users
Requirements Users can create auction listings with a start price, reserve price, and end time Users place bids; highest bid
Requirements Track real-time location of mobile assets (drivers, delivery couriers, field workers) 1M active devices sending location updates every 4
What is a Data Pipeline? A data pipeline is a sequence of data processing steps: collect → transform → store
Permission Models Overview Three main models: ACL (Access Control List): per-resource list of who can do what. Simple, fine-grained, but
Requirements Create and manage discount coupons (percentage, fixed amount, free shipping) Apply coupon to a cart: validate, compute discount, prevent
