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SYSTEM DESIGN · FREE

System design, one rung at a time

Concepts first, then the technologies and building blocks, then the patterns, then the design questions interviewers ask. Every item is an animated walkthrough with notes and interview questions, and the app brings each one back for two revisions.

Start episode 1 → The LADDER method
  • 115 walkthroughs live
  • 115 on the path
  • 296 interview Q&As
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The path

Six tracks that build on each other. Start at the top; each page says what it needs from the ones before.

  1. 1ConceptsHow the web and distributed systems work, from DNS to consensus.41 of 41 live
  2. 2TechnologiesPostgreSQL, Cassandra, Redis, Kafka and friends: when to use which, and why.12 of 12 live
  3. 3Building BlocksLoad balancer, cache, queue, key-value store: one component at a time.14 of 14 live
  4. 4PatternsThe 7 situations that repeat across problems, and the standard moves.7 of 7 live
  5. 5How to answerThe LADDER method: six steps for any design question in 45 minutes.Live
  6. 6Design ProblemsURL shortener to Uber: the questions interviewers ask, step by step.41 of 41 live

Concepts: 41 episodes in 5 levels

A How the web works 7 of 7 live B Services and how they talk 8 of 8 live C Databases 9 of 9 live D Distributed systems 10 of 10 live E Running it in production 7 of 7 live

Beyond the concepts

Technologies

Building blocks

Patterns

Design problems

New videos every day. Follow on YouTube or Instagram to catch each one.

Pair it with DSA practice

Interviews test both. Practise 231 DSA problems grouped by pattern, with Java solutions, animated walkthroughs and a revision schedule.

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