System Design
Study notes and quick-revision quizzes. Modules are in study order — start at 1 and work down.
Requirements, estimation, constraints, trade-offs — the 5-step framework.
HLD building blocks, 3-tier, storage, LB/CDN placement, API & protocol styles.
Consistent hashing, bloom filters, HLL/CMS, rate limiting, ID generation, geo-indexing, LSM vs B-tree.
SQL vs NoSQL, data modeling, replication, sharding, CAP/PACELC, consistency, search, analytics.
Scaling patterns, statelessness, queues, rate limiting, load shedding, cell-based.
Cache patterns, invalidation, hot keys, tail latency, Little's Law, load testing.
Retries, timeouts, circuit breaker, bulkhead, failover, backups, DR, idempotency, chaos.
Metrics, logging, tracing, SLI/SLO/SLA, error budgets, alerting, incident response.
AuthN/AuthZ, JWT, tokens, password hashing, RBAC, OAuth2/OIDC, encryption, API abuse, PII.
Consensus, clocks, quorum, locks, 2PC, gossip, CRDT.
Event-driven basics, webhooks, Kafka internals, CQRS, event sourcing, saga, outbox.
SOLID applied, GoF patterns, UML, interfaces, concurrency, DDD-lite, problem set.
WebSocket at scale, session routing, presence, fan-out, push pipelines.
CI/CD, canary, feature flags, multi-region topologies, DR (RTO/RPO), cell architecture.
~30 end-to-end designs (HLD + LLD). One every 2–3 days once past Module 5.
Senior/staff format, company formats, design docs, trade-off delivery, mocks.
RAG, vector DBs, LLM serving, guardrails, eval. Any time after Module 12.