failover

Interactive System Design Platform

Learn system design
by doing it.

Design each system yourself, and see how it holds up under load - from one server to distributed systems.

Design your first system See the labsSee the path

38 modules · 303 lessons · 47 labs · ~78 hours · + 86 system labs

Practice systems
using interactive labs

20k/s6.7k/s6.7k/s6.7k/s6.7k/s6.7k/s6.7k/s4.2k/s
Client
20k req/s
99% reads · 1% writes
Load balancer
20k / 200k req/s
10%
API server 1
6.7k / 10k req/s
67%
API server 2
6.7k / 10k req/s
67%
API server 3
6.7k / 10k req/s
67%
Cache
20k / 100k req/s
20%
Database
4k r · 200 w/s
69%
Try deleting me

Live at ~20k requests/s. Select a server and press Delete (or ×) and watch the rest take its load.

Where to start

New to system design?

  1. What is system design?
  2. Start with a simple system
  3. Caching
  4. When one server isn't enough
  5. When one database isn't enough

Follow the path

38 modules, from one server to distributed systems, in the order a growing app needs them. Read each idea, then build it.

Start the path

Know the basics?

Practice in the labs

Pick one of 86 apps you use every day, design it from a blank page, then put it under load and fix whatever breaks.

See the labs

Structured lessons, from zero to distributed systems

Every module builds on the one before, in the order a growing app needs it.

Foundations

Part 1 · 10 modules · 87 lessons

  1. 1What is system design?
  2. 2Start with a simple system
  3. 3Caching
  4. 4When one server isn't enough
  5. 5When one database isn't enough
  1. 6Live updates
  2. 7Background jobs
  3. 8Rate limiting
  4. 9Growing big
  5. 10Putting it together

Distributed systems

Part 2 · 8 modules · 69 lessons

  1. 11Microservices
  2. 12Problems in distributed systems
  3. 13Replication in depth
  4. 14Partitioning in depth
  1. 15Messaging: Kafka and pub/sub
  2. 16Transactions across services
  3. 17Events and streams
  4. 18Availability and going global

Under the hood

Part 3 · 1 module · 10 lessons

  1. 19Classic algorithms in action

    Toolbox

    Part 4 · 5 modules · 39 lessons

    1. 20Traffic and the edge
    2. 21Choosing a data store
    3. 22Staying up
    1. 23Async and event-driven
    2. 24Whole systems

    AI systems

    Part 5 · 14 modules · 98 lessons

    1. 25ML for engineers
    2. 26How LLMs work in systems
    3. 27Retrieval-augmented generation (RAG)
    4. 28LLM gateways
    5. 29Evaluating AI systems
    6. 30Safety and security for AI systems
    7. 31AI agents
    1. 32Agent protocols and orchestration
    2. 33Serving AI at scale
    3. 34Prompt and context engineering
    4. 35Data pipelines for AI
    5. 36Multimodal and real-time AI
    6. 37AI cost and operations
    7. 38Capstone designs

    See every lesson on the path

    Common questions

    Do I need to know system design already?

    No. The path starts from one server and one database, and adds a part only when the numbers demand it.

    What is a lab?

    A canvas where you build a system from components, put it under load, and watch what breaks. Each step has goals that check your design.

    How are labs checked?

    A capacity model sends your traffic through the design. Each component has a limit and a monthly cost; anything over its limit turns red.

    Where does the content come from?

    Lessons and labs are structured data. An admin enters a topic in the Studio, Claude drafts the content, and it is validated before anyone can read it.

    Is my progress saved?

    Yes, in your browser. Nothing leaves your device.

    Design your first system this week.

    Start the first lab