Scaling, architecture styles, storage, queues, reliability and SD interview methodology
Foundations & Scaling
Backend layers, vertical and horizontal scaling, stateless services, load balancing, capacity estimation, latency percentiles, SLA/SLO, concurrency models
Architecture Styles
Monolith and microservices, service boundaries, layered and hexagonal architecture, DDD, CQRS, event sourcing, API Gateway and BFF, migration and antipatterns
Data & Storage
Database choice, indexes, transactions and isolation, locking, replication, sharding and partitioning, caching, pagination, zero-downtime migrations
Messaging & Consistency
Queues and brokers, delivery guarantees, idempotency, transactional outbox, sagas and compensations, eventual consistency, message ordering, event schema evolution
Reliability & Resilience
Timeouts and retries, circuit breaker, resource isolation, rate limiting, cascading failures, graceful shutdown, health checks, degradation, rollouts and postmortems
Interview Method & Case Studies
System design interview framework, requirements gathering and back-of-the-envelope estimation, typical cases: URL shortener, feed, chat, payments, notifications, search, booking