Easy Learn
Designing a Compromised Merchant Fraud Detection System How to catch a merchant account that has been hijacked and is being used to push fraudulent transactions at unusually high volume — before it drains real money out of the payment network, and without accidentally freezing a legitimate merchant on their biggest…
A real-time multi-language translation system for posts and comments — built from first principles How do platforms show a post written in Japanese to a reader in Brazil, in Portuguese, within a fraction of a second — and do the same for millions of comments arriving every minute, in over…
Detecting account sharing and credential leaks before they turn into a breach A ground-up, beginner-friendly system design walkthrough of how large platforms build the pipelines, models, graph databases, and streaming infrastructure that spot one account being used from two continents at once — and decide, in milliseconds, what to do…
Designing for a viral post: handling 10 million views in one hour without taking the rest of the platform down A beginner-friendly, step-by-step system design walkthrough of how large-scale platforms detect, absorb, and isolate a sudden hot-key traffic spike — the kind that happens when one post, tweet, or video suddenly…
Designing a Stock Trading Platform: Matching Engine System Design A system design deep dive into building a matching engine that processes buy/sell orders with strict ordering guarantees and sub-millisecond matching latency, scaled to millions of requests per minute — architecture, algorithms, trade-offs, and the questions an interviewer will ask you…
Designing a Card Testing Fraud Detection System A complete, from-first-principles walkthrough of how to design a real-time system that catches stolen-card “test transactions” before they turn into real financial loss — architecture, algorithms, trade-offs, and the questions an interviewer will ask you about it. 01 · Intro & History02 ·…
Split Payments — Charging One Purchase Across Multiple Payment Methods A complete system-design guide to a checkout that can divide a single purchase amount across a gift card, store credit, and a credit card in one atomic transaction — with correctness guaranteed even at a million requests per minute. 01…
What Is Edge Computing? A complete, beginner-friendly, production-ready guide to edge computing — what it is, why it exists, how it works internally, and how companies like Netflix, Amazon, and Uber use it in the real world. 01 · Intro & History02 · Problem03 · Core Concepts04 · Architecture05 ·…
What Is a Write-Behind Cache? A complete, beginner-friendly guide to write-behind (write-back) caching — how it works, why it exists, how to build one, and how companies like Netflix and Amazon use it in production. 01 · Intro & History02 · Problem03 · Core Concepts04 · Architecture05 · Internal Working06…
“Why Should We Hire You as Our Architect? Six words that can make even a confident, experienced professional go a little blank. Let’s slow this question down, take it apart gently, and build an answer that actually sounds like you. 00 · Introduction01 · Why They Ask02 · The Mistakes03…