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For software engineers preparing for a system design interview or moving into distributed systems. Follow a request through caches, queues and databases, then test what you learned in labs, case studies and quizzes.
Open any logo to see how it works.
Open any number to see what is behind it.
Cracking the system design interview, or growing into a staff or architect role? A path sets the order for you across lessons, labs and designs. Open one to see every step.
Start here
Learn how the web works, how data is stored, and the building blocks every system shares, then design your first system end to end.
Follow this pathWhat system design is, how to size a system on paper, and the numbers worth knowing.
Clients, servers, HTTP and how a request travels.
Encrypted connections, sign-in, sessions and single sign-on: the security every product needs on day one.
Tables, schemas and indexes: how data is stored and found quickly.
Package apps reproducibly so they run anywhere.
Vertical vs horizontal scaling and spreading load.
Keep hot data close; learn eviction and invalidation.
Push data to clients without polling.
Put it together: design a URL shortener from requirements to scale, and learn how ids are generated.
Each system design course goes deep on one subject, in six stages from foundations to interview practice.
Requirements, estimates and the core parts of every system, and when to use each.
The core ideas behind every large system, in short lessons: scaling, storage, caching, consistency, queues, reliability and a full worked design.
You will be able to
Starts with
The mechanisms underneath: transactions, indexes, HTTPS, network layers, Redis and Kafka.
Worked designs from a rate limiter to video streaming, then from requirements to classes: SOLID, patterns and a parking lot.
Consensus, storage engines, Kafka internals and resilience, then messaging and microservice patterns.
Documents, maps, payments and exchanges, plus search, analytics and big-data platforms.
A method for system design interviews, practice problems and quick-reference sheets for trade-offs and numbers.
The core ideas behind every large system, in short lessons: scaling, storage, caching, consistency, queues, reliability and a full worked design.
You will be able to
Starts with
See how caching, sharding, queues and consensus connect, then follow any of them to the lessons that teach it.
Topics link where the library covers them together. Drag to turn the model, then pick one to see what it connects to.
Open one for the lessons that teach it, in reading order.
Spread traffic across servers with L4/L7 balancing, health checks and algorithms.
Cache-aside, write-through, eviction and invalidation strategies.
Serve content from edge locations close to users.
Schemas, indexes, query plans and choosing a store.
Partition data across nodes by key, range or directory.
Leader/follower, multi-leader and leaderless replication.
Consistency, availability and partition tolerance trade-offs.
Token bucket, leaky bucket and sliding-window limiters.
Distributed commit log for event streaming at scale.
Decompose systems into independently deployable services.
Timeouts, retries, circuit breakers, bulkheads and load shedding.
Metrics, logs, traces, SLOs and alerting.
Pick a hard problem. See how Netflix, Uber or WhatsApp deal with it, from the architecture to the trade-offs.
Amazon
Three questions in the style of a system design interview. Every answer comes with the reason.
Scenario · question 1 of 3
Answer as you would in a design review.
You will see straight away whether it holds up, and why. Nothing is saved, so guess freely.
Turn an answer into a working design. Put the parts together, send traffic through them and see what gives way first.
Requirements, estimates, components and trade-offs, in the order you would use them in a real design review.
System design is deciding which parts a software system needs and how they work together, so it stays fast and reliable as it grows: load balancers, caches, databases, queues and the trade-offs between them. Interviews test it because senior engineers do it every day.
Yes. The lessons, code labs, learning paths and the curated resource library are free to read and use, with no paywall in front of the fundamentals.
No. Open any lesson and begin. Your progress and bookmarks are kept in your browser on this device.
Start with System Design Foundations, the first course on this page, or open the Beginner learning path. It starts with how the web works and how data is stored, then builds to designing a first system end to end.
Yes. The Interview Preparation course gives you a method and a bank of practice problems mapped to the lessons that help with each, and the Interview Ready path sets the order. The quizzes let you check yourself as you go.
Rate limiters, news feeds, chat systems, search autocomplete, video streaming, file storage and URL shorteners come up again and again, and AI products such as coding assistants are now asked too. The Classic System Designs course works through most of these step by step, Real-World Systems includes an AI coding assistant, and the design challenges let you try them yourself.
They are articles, talks, repositories and papers from engineering teams and creators around the web. Every one links to the original with credit, and resources belong to their owners.
Yes. Run code labs, push traffic through the simulators, sketch a design in the System Builder, and check yourself with quizzes and practice problems.