System Design Pocket Guide

Walk into the system design interview with a framework you can apply to any prompt - not a pile of memorised diagrams that fall apart under follow-up questions.

Forty-five minutes. A blank whiteboard. "Design a URL shortener." "Design WhatsApp." "Design Uber." Most candidates blank on requirements, skip the back-of-envelope math, draw boxes without arrows, and never reach the trade-offs that decide hire vs. no-hire. The interviewer has heard every textbook answer a thousand times. What separates the offers from the rejections is a repeatable structure you can run on any system, under pressure, while talking out loud.

System Design Pocket Guide: Interviews is the working candidate's prep book for FAANG-level loops and senior promo panels. Across 15 worked designs in 5 parts, every chapter follows the same six-step framework so the structure becomes muscle memory by the time you hit the real interview:
• Requirements - functional and non-functional, the clarifying questions that prove you think before you draw.
• Back-of-envelope estimation - QPS, storage, bandwidth, the math interviewers actually want to see.
• High-level design - the boxes, the arrows, the read and write paths drawn cleanly.
• Deep dive - the one or two components the interviewer will push on, with real schemas and algorithms.
• Trade-offs - consistency vs. availability, push vs. pull, SQL vs. NoSQL - with a defensible pick, not a shrug.
• Common mistakes - the failure modes interviewers fish for, and how to head them off before you get asked.

The fifteen designs:
• Part I - Web-Scale Basics: URL Shortener, Rate Limiter, Key-Value Store.
• Part II - Social & Real-Time: News Feed, Chat System, Notification System.
• Part III - Content & Media: Video Streaming, Image Hosting, Search Engine.
• Part IV - Infrastructure: Distributed Cache, Task Scheduler, Monitoring System.
• Part V - Advanced: Payment System, Ride-Sharing, Collaborative Editor.

Every chapter is opinionated. When the answer is "use Cassandra," it says so - and explains why over Postgres for that specific workload. When push beats pull for the news feed of a celebrity with 50 million followers, the math is on the page. When sequential keys leak business secrets in the URL shortener, the fix is shown. No fluff, no "it depends" without a follow-up.

Concepts are explained alongside the architecture - consistent hashing, leader election, quorum reads, vector clocks, geohashing, CRDTs, the WAL, sharding strategies, replication topologies. You will not be sent to Wikipedia mid-chapter. Trade-off tables, common-mistakes lists, and a cross-design reference card at the end give you something to revisit the night before the interview.

Who this book is for: backend, full-stack, and platform engineers prepping for FAANG-level system design loops, senior or staff promo panels, or any interview where "tell me how you'd design X" decides the offer. Assumes you know what a database and a load balancer are; assumes nothing about distributed systems jargon.

Other books in Pocket Guides for Developers (standalone, no reading order):
• System Design Pocket Guide: Fundamentals
• This book - System Design Pocket Guide: Interviews
• AI Agents Pocket Guide
• Prompt Engineering Pocket Guide
• Database Playbook
• LLM Observability Pocket Guide
• Event-Driven Architecture Pocket Guide
• RAG Pocket Guide