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Fan Out Guides

Fan Out in System Design

2 in-depth guides covering how fan out is used in real system design interviews. Learn when to use it, its trade-offs, and how to discuss it with confidence at companies like Amazon, Google, Goodreads.

Dec 10, 2025•20 min

How to Design an Online Book Review System - Complete System Design Guide

Master online book review system design for your next big tech interview. Covers database schema, denormalised rating counters, Bayesian average ratings, Elasti...

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Oct 20, 2025•22 min

How to Design Instagram / a Social Feed - Complete System Design Guide

Master Instagram and social feed system design for your next big tech interview. Learn the hybrid fan-out approach, how Instagram's real tech stack works, feed ...

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Go Beyond Reading About Fan Out

Fan Out concepts show up across many system design interviews. Practice applying them in full interview simulations and get actionable feedback.

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Companies That Test Fan Out

Amazon Audible Dropbox Goodreads Google Meta Microsoft Scribd