Alex Xu’s System Design Interview is the most recommended book in tech hiring. Volume 1: $39.99 on Amazon. Volume 2: $40.00 on Amazon. Both together: $79.99. Thousands of engineers have bought them. Millions have been told to buy them. Every tech interview prep list on the internet includes these two books. In December 2024, one engineer at AWS read both volumes cover to cover. His name is Gaurav Kumar. CS grad from USC. Day job at Amazon Web Services. He goes by liquidslr on GitHub. He took notes on every single chapter. Organized them by topic. Linked every section to the original research papers from Amazon, Google, and Discord. Then he pushed the whole thing to GitHub for free. Then he built a free website to read them on. He named it Pagefy. Every chapter. Every diagram concept. Every system. Free. Forever. Here is what is inside: → Chapter 1: Scale From Zero To Millions Of Users → Chapter 2: Back-of-the-Envelope Estimation → Chapter 3: A Framework For System Design Interviews → Chapter 4: Design A Rate Limiter → Chapter 5: Design Consistent Hashing → Chapter 6: Design A Key-Value Store → Chapter 7: Design A Unique ID Generator In Distributed Systems → Chapter 8: Design A URL Shortener → Chapter 9: Design A Web Crawler → Chapter 10: Design A Notification System → Chapter 11: Design A News Feed System → Chapter 12: Design A Chat System → Chapter 13: Design A Search Autocomplete System → Chapter 14: Design YouTube → Chapter 15: Design Google Drive → Chapter 16: Proximity Service And that is Volume 1. Volume 2 continues: → Nearby Friends → Google Maps → Distributed Message Queue → Metrics Monitoring and Alerting System → Ad Click Event Aggregation → Hotel Reservation System → Distributed Email Service → S3-like Object Storage → Real-Time Gaming Leaderboard → Payment System → Digital Wallet → Stock Exchange Here is why this matters: Every FAANG company asks system design questions. Google. Amazon. Meta. Microsoft. Apple. Netflix. Uber. Airbnb. Stripe. The median software engineer at these companies makes $226,000. Senior makes $312,000. Staff makes $457,000. The interview that stands between you and that salary is system design. The book that everyone says to read costs $79.99. The official video course on ByteByteGo costs $499 for lifetime or $189 a year. Hello Interview charges $279 lifetime. Educative charges $59 a month. These notes cover the same 28 chapters as the books. For $0. Not a summary. Not a cheatsheet. Structured notes with diagrams, key concepts, and source papers for every chapter of both volumes. Browse them as a website at http://pagefy.io. Search any topic. Jump to any chapter at 1 AM the night before the interview. 5,555 stars. 1,059 forks. One AWS engineer on his own time. One honest flag: there is no LICENSE file on the repo. These are study notes summarizing a copyrighted book. If you can afford $79.99, buy the books. Alex Xu deserves the royalty. These notes are for the night before, when you already read the book and forgot half of it. One engineer. Two books. Twenty eight chapters. Free on GitHub. The book teaches you the answers. This repo helps you remember them.

Pagefy — System Design Notes & Technical Book Summaries

Source: https://pagefy.io/

Data Structures and Algorithms

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