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.
Core Entities Member: member_id, user_id, first_name, last_name, email, phone, photo_url, join_date, status (ACTIVE, SUSPENDED, CANCELLED, FROZEN), emergency_contact. MembershipPlan: plan_id, name […]
Requirements An analytics dashboard lets users visualize business metrics: revenue over time, active users, conversion rates, funnel analysis, A/B test
Core Entities Vehicle: vehicle_id, vin (unique), make, model, year, type (SEDAN, VAN, TRUCK, ELECTRIC), status (AVAILABLE, ASSIGNED, IN_MAINTENANCE, OUT_OF_SERVICE), current_driver_id,
What is a CDN and Why Does It Matter? A CDN is a geographically distributed network of edge servers that
Core Entities Problem: problem_id, title, slug, difficulty (EASY, MEDIUM, HARD), statement_markdown, constraints, time_limit_ms, memory_limit_mb, tags (array), is_active. TestCase: tc_id, problem_id,
Requirements A payment gateway processes card transactions between merchants and issuing banks. Core flow: customer enters card details → merchant
Core Entities Warehouse: warehouse_id, name, address, total_locations, is_active. Location: location_id, warehouse_id, zone (RECEIVING, STORAGE, STAGING, SHIPPING), aisle, bay, level, bin,
Requirements A location service has two core functions: proximity search (find entities near a given coordinate — restaurants, drivers, friends)
Core Entities Cinema: cinema_id, name, address, timezone. Hall: hall_id, cinema_id, name, total_rows, total_cols, layout_type (STANDARD, IMAX, VIP). Seat: seat_id, hall_id,
Requirements A gaming backend handles player authentication, matchmaking (pairing players of similar skill), real-time game state synchronization, leaderboards, and player
Why Multi-Region? A single-region architecture has three critical weaknesses: latency (a user in Tokyo hitting servers in us-east-1 has ~150ms
Core Entities Product: product_id, sku (unique stock keeping unit), name, description, category_id, unit_cost, unit_price, weight_kg, dimensions_cm (JSON), is_active. Warehouse: warehouse_id,
Core Entities Driver: driver_id, user_id, vehicle_id, license_number, status (OFFLINE, AVAILABLE, ON_TRIP), current_lat, current_lng, last_location_update, rating, total_trips, acceptance_rate. Vehicle: vehicle_id, driver_id,
Requirements A media storage and delivery system stores uploaded videos or images and delivers them efficiently to users worldwide. Think
Requirements A typeahead service returns query suggestions as the user types. Google Search autocomplete, Twitter’s hashtag completion, and Stripe’s dashboard
