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 Survey: survey_id, creator_id, title, description, status (DRAFT, ACTIVE, PAUSED, CLOSED), settings (JSONB: allow_anonymous, one_response_per_user, show_progress_bar, randomize_questions, response_limit), start_date, […]
Core Entities Poll: poll_id, creator_id, question, poll_type (SINGLE_CHOICE, MULTIPLE_CHOICE, RANKED, RATING), status (DRAFT, ACTIVE, CLOSED), is_anonymous, allow_change_vote, visibility (PUBLIC, PRIVATE,
Geospatial Data Fundamentals Geospatial queries are common in production systems: “find the 10 nearest restaurants,” “is this user inside a
Core Entities Cart: cart_id, user_id (NULL for guest), session_id (for guest carts), status (ACTIVE, ABANDONED, CHECKED_OUT), currency, created_at, updated_at, expires_at.
Core Entities Home: home_id, owner_id, name, address, timezone, created_at. Room: room_id, home_id, name, floor_number. Device: device_id, home_id, room_id, name, type
Why Distributed Caching? A single application server’s in-memory cache is lost on restart and not shared across instances. A distributed
What is an API Marketplace? An API marketplace (like Stripe, Twilio, RapidAPI, or AWS API Gateway) lets external developers discover,
Core Entities Tenant: tenant_id, name, slug, plan, custom_domain, storage_quota_gb, created_at. (Multi-tenant: each customer organization is a tenant with isolated content.)
Feed Architecture Overview A social feed shows users content from people and pages they follow, ranked by predicted engagement. The
Core Entities Member: member_id, user_id, program_id, tier (BRONZE, SILVER, GOLD, PLATINUM), points_balance, lifetime_points (never decrements — used for tier calculation),
The Three Pillars of Observability Metrics: numerical measurements over time (request rate, error rate, latency percentiles, CPU usage). Low cardinality,
Data Lake vs. Data Warehouse A data warehouse stores structured, schema-on-write data optimized for SQL analytics (Redshift, BigQuery, Snowflake). A
Core Entities Customer: customer_id, name, email, phone, default_address, stripe_customer_id. Restaurant: restaurant_id, name, address, location (lat/lng), cuisine_type, rating, is_open, prep_time_minutes, operating_hours.
Core Entities User: user_id, email, name, quota_bytes, used_bytes. Document: document_id, owner_id, name, mime_type, current_version_id, parent_folder_id, is_deleted (soft delete), created_at, updated_at.
What is a Blockchain Explorer? A blockchain explorer is a read-only interface to blockchain data — like a search engine
