Phase 0 of 9 · 4 lessons
How system design interviews work
Learn the step-by-step way to answer any design question before you learn the parts. Without a method, even good knowledge comes out messy under pressure.
Interviewers grade how you think: do you ask the right questions, size the problem, start simple and then improve the weak spots? A clear method shows all of that, even when you don't know every technology.
Lessons, in order
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0.1
Meet the building blocks: a map of a typical web system
Most large web systems are built from the same dozen parts — clients, DNS, a CDN, load balancers, app servers, caches, databases, queues, workers and object storage — connected in a familiar shape.
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0.2
The high-level design interview: a step-by-step answer framework
A repeatable order of steps for answering any 'Design X' question in about 45 minutes.
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0.3
Back-of-the-envelope estimation
Quick, rough maths to estimate traffic, storage and bandwidth, so your design decisions are based on scale.
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0.4
The low-level design interview: a step-by-step approach
A repeatable way to answer 'Design the classes for X' (a parking lot, an elevator, Splitwise) and write the key code.