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Interview Pen
Full system design walkthroughs with whiteboard diagrams and a clear structure.
By Interview Pen · Interview Pen · Added 2026-10-22
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Overview before you open it
A talk or video. Watch it with a pause button handy: it is easiest to follow once you know the basic vocabulary.
- Who it suits
- You know the basics (caching, queues, replication) and want to see them applied.
- From
- Interview Pen: see more from them
- Design areas it touches
- Scaling and performanceLearning and interview prep
This overview is generated from the title, tags and where we use the resource; it is not a summary of the content. The original is by Interview Pen.
Study it, do not just read it
Before
Before you open it, spend two minutes sketching how you would build this yourself. Write down the biggest risk you can see.
While you read
- Which number or limit forced their main decision?
- What did they try first, and why did it stop working?
- What did they choose not to build?
After
- What would break first if traffic grew tenfold?
- What did they trade away to get what they wanted?
- Explain the design in three sentences, without looking.
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