Who is this System Design course for?

Anyone who builds or will build software: students, developers moving into backend or architecture work, and engineers preparing for system design interviews. The first course assumes no prior knowledge.

Do I need to know a programming language?

No. The lessons explain ideas with diagrams, tables and plain language. A few lessons include short code or configuration sketches, but you can follow them without writing code.

Yes. The first lesson of each course is open to everyone, and a free account unlocks the rest, tracks your progress and keeps your place.

Where should I start?

Start with System Design Foundations. If you already know the basics (load balancers, caches, databases), start with Building Blocks, and take the Advanced course and case studies when you are comfortable with replication, sharding and consistency.

Will this get me through a system design interview?

It teaches the concepts, the way to reason about trade-offs, and six worked case studies you can practise out loud. No course can promise an interview result, so practise the exercises and explain your designs to another person.

Back to courses

Learning path

System Design, from first principles to real systems

40 lessons in three courses, from your first design to distributed-systems trade-offs and complete case studies. Plain-English explanations, diagrams, trade-off tables and practice exercises in every lesson.

Three courses, one path

Start at your level. Each course builds on the one before it.

TrackStarter ~12.5 hr12 lessons

System Design Foundations: From Zero to Your First Design

Start here if system design is new to you. Learn how to turn requirements into a design, estimate load, and use the basic building blocks (DNS, load balancers, caches, databases, CDNs) with plain-English explanations and diagrams.

Lessons in this track

Not started0 / 12 lessons

TrackIntermediate ~14.5 hr14 lessons

System Design Building Blocks: Data, Messaging and Scale

The intermediate course: replication, sharding, consistency, advanced caching, queues and streaming, API gateways, rate limiting, search, storage engines, observability and security, with the trade-offs behind each choice.

Lessons in this track

Not started0 / 14 lessons

TrackAdvanced ~15.5 hr14 lessons

Advanced System Design and Case Studies

The advanced course: distributed transactions, CQRS and event sourcing, consensus, clocks and ordering, resilience, multi-region design and capacity planning, then full case studies: URL shortener, photo sharing, news feed, chat, video streaming and ride sharing.

Lessons in this track

Not started0 / 14 lessons

What you will be able to do

Turn a vague idea into clear functional and non-functional requirements.
Estimate traffic, storage and bandwidth before you draw a single box.
Choose between caches, queues, databases and replication, and explain the trade-off.
Design for failure: timeouts, retries, circuit breakers and graceful degradation.
Reason about consistency, ordering and distributed transactions.
Walk through complete designs: URL shortener, photo sharing, news feed, chat, video streaming and ride sharing.

Tools you will meet

The lessons teach the ideas first and use these widely used tools as examples. Naming a tool is not an endorsement, and every design in the course works with equivalents.

Data and caching

PostgreSQLRelational database
MySQLRelational database
MongoDBDocument database
Apache CassandraWide-column database
DynamoDBManaged key-value database
RedisIn-memory cache and data store
MemcachedIn-memory cache
OpenSearchSearch and analytics engine
ElasticsearchSearch engine
Amazon S3Object storage

Messaging and events

Apache KafkaDistributed event log
RabbitMQMessage broker

Traffic and platform

NginxWeb server, reverse proxy, load balancer
EnvoyProxy for gateways and service meshes
KubernetesContainer orchestration
etcdConsensus-backed key-value store
TerraformInfrastructure as code

Observability

PrometheusMetrics and alerting
GrafanaDashboards

Names and logos are trademarks of their respective owners and are shown only to identify the tools.

The whole subject on one page

This cheat sheet maps the territory: requirements, the high-level architecture, the request lifecycle, scaling techniques, reliability, data trade-offs, security and the common myths. The first lesson explains every part of it in text.

Read System Design: The Big Picture

System Design cheat sheet: requirements, high-level architecture, request lifecycle, scaling techniques, reliability, data and distributed systems, security and operations, common myths and a practical checklist

Case studies

Full designs worked end to end: requirements, estimation, API, data model, architecture, bottlenecks and trade-offs. For a longer worked example, read the notification service design.

Questions

Who is this System Design course for?: Anyone who builds or will build software: students, developers moving into backend or architecture work, and engineers preparing for system design interviews. The first course assumes no prior knowledge.
Do I need to know a programming language?: No. The lessons explain ideas with diagrams, tables and plain language. A few lessons include short code or configuration sketches, but you can follow them without writing code.
Is it free?: Yes. The first lesson of each course is open to everyone, and a free account unlocks the rest, tracks your progress and keeps your place.
Where should I start?: Start with System Design Foundations. If you already know the basics (load balancers, caches, databases), start with Building Blocks, and take the Advanced course and case studies when you are comfortable with replication, sharding and consistency.
Will this get me through a system design interview?: It teaches the concepts, the way to reason about trade-offs, and six worked case studies you can practise out loud. No course can promise an interview result, so practise the exercises and explain your designs to another person.