Learn
How big systems are built
From how one bit is stored to designing WhatsApp and Uber: simulators, games, company stories and interview practice.
Foundations
The vocabulary and habits behind every design: how to approach a problem, scale, availability, latency and quick estimates.
0 / 5 lessons finished
- 1How to approach a design interviewA repeatable template: time budget, requirements that change the design, estimation drill, a sketch that grows from a baseline, trade-offs with numbers, and the skipped question.25 min▶ Start
- 2Scaling: up vs out, stateless vs statefulWhy one machine hits a ceiling, why more machines are not free, stateless vs stateful servers, read-replica limits, headroom, and scaling into a wall.25 min▶ Start
- 3Availability and the ninesThe nines in minutes, chained dependencies, redundancy and its ceiling, failover time, a simulated lifetime, and the cascade.25 min▶ Start
- 4Latency, throughput and percentilesLittle's law, batching, why averages lie, latency budgets, the queueing hockey stick, merging percentiles correctly, and the slow-one-in-a-hundred fan-out.30 min▶ Start
- 5Back-of-envelope estimationSizing users, QPS, storage, bandwidth, cache and servers in two minutes, with worked sheets for four systems and the slips that make an estimate ten times wrong.30 min▶ Start
Memory & Storage
How a computer remembers: cache, RAM, SSD and hard disk, from the physics of one bit to why each is fast or slow.
0 / 4 lessons finished
Caching & Databases
Making data fast: caches, Redis, indexes, what a database does on every read and write, and how to choose one.
0 / 8 lessons finished
Scaling Data
When one database is not enough: replication, sharding, consistent hashing, IDs, object storage and search.
0 / 7 lessons finished
Networking & Traffic
How a request travels and gets managed: DNS, TCP, load balancers, proxies, API gateways, CDNs, rate limits and API styles.
0 / 7 lessons finished
Queues & Streaming
Letting services talk without waiting: queues, logs, Kafka, events, and delivery guarantees.
0 / 5 lessons finished
Distributed Systems Core
What changes when many machines cooperate: CAP, consistency, consensus, failure detection, clocks, locks and transactions.
0 / 11 lessons finished
Reliability & Operations
Staying up when things break: timeouts, retries, circuit breakers, observability, SLOs, deployments, disaster recovery and security.
0 / 9 lessons finished
Architecture Patterns
The big shapes a system can take: client-server, microservices, serverless, event-driven, peer-to-peer, CQRS and service mesh.
0 / 7 lessons finished
Design Interviews
Put it all together: the classic full designs, step by step, with the trade-offs an interviewer probes.
0 / 15 lessons finished