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LearnLevels 0 to 6

System design, level by level

From your first server to interview-ready: seven levels of lessons, plus challenges to build what you learn.

51 lessons · 19 challenges · about 16 h

Level 0: Starter track

How the web works, from zero: requests, servers, databases and APIs.

How the web works

  • Basic21 min
  • Basic18 min
  • Basic18 min
  • Basic17 min

Level 1: Foundations and building blocks

Latency, estimation, databases, and the first tools for scale: load balancers and caches.

Fundamentals

  • Going deeper19 min
  • Going deeper17 min

Networks and APIs

  • Going deeper17 min
  • Going deeper20 min

Scaling out

  • Going deeper17 min
  • Going deeper17 min
  • Going deeper20 min
  • First traction
    Challenge

Staying up when things break

Level 2: Data at scale

Replication, queues and complete systems, plus surviving failures.

Data and async work

  • Advanced18 min
  • Advanced21 min
  • Advanced21 min
  • Going viral
    Challenge
  • Sale night
    Challenge

Files and front doors

  • Advanced20 min
  • Advanced19 min
  • Photo day
    Challenge
  • Bot attack
    Challenge

Classic designs

  • Advanced19 min
  • Advanced19 min

End to end

  • Advanced20 min

Level 3: Distributed systems

Keeping data correct and apps standing when many machines work together: consistency, consensus, failures and messaging.

Keeping data correct

  • Advanced20 min
  • Advanced19 min
  • Advanced20 min
  • Advanced18 min
  • Advanced17 min

Surviving failure

  • Advanced20 min
  • Advanced18 min
  • Advanced19 min
  • Flaky Friday
    Challenge
  • The database blinks
    Challenge

Messages and events

  • Advanced20 min
  • Advanced18 min

Level 4: Classic problems

The designs interviewers ask for, built from everything so far: chat, feeds, notifications, search, video and more.

Social and messaging

  • Advanced19 min
  • Advanced18 min
  • Advanced16 min
  • Chat launch
    Challenge
  • Feed day
    Challenge
  • Campaign night
    Challenge

Search and media

  • Advanced17 min
  • Advanced21 min
  • Typing speed
    Challenge
  • Premiere night
    Challenge

Money, maps and tickets

  • Advanced21 min
  • Advanced18 min
  • Advanced21 min
  • Advanced20 min
  • Rush hour rides
    Challenge
  • Payday
    Challenge
  • Tatkal 10 AM
    Challenge

Infrastructure

  • Advanced19 min
  • Advanced20 min
  • Crawl day
    Challenge
  • Cart storm
    Challenge

Level 5: Modern systems

What production teams work on today: AI apps, streaming data, staying observable, surviving region failures, shipping safely and keeping users secure.

Data in motion

  • Advanced18 min
  • Advanced18 min

Running in production

  • Advanced17 min
  • Advanced20 min
  • Advanced19 min
  • Advanced20 min
  • Region down
    Challenge

Level 6: Interview ready

The system design round itself: a 45-minute plan, requirements and quick estimates, trade-offs, and how interviewers grade you. Then practise with the AI mock interviewer.

The interview round

  • Advanced19 min
  • Advanced16 min
  • Advanced17 min
  • Advanced19 min