Easy Learn
A complete, beginner-to-production system design walkthrough for a real-time checkout A/B testing platform: deterministic edge-resolved bucketing, async Kafka-backed event ingestion, sequential-testing-safe statistics, guardrail-driven auto kill switches, and everything else needed to safely measure the effect of checkout-flow variants at a million-plus requests per minute without ever slowing checkout down.
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 ·…
Designing a Card-Testing Botnet Fraud Detection System A production-grade, interview-ready deep dive into stopping card-not-present (CNP) fraud where a botnet hammers your payment gateway with thousands of stolen card numbers simultaneously — while staying fast, fair to legitimate customers, and resilient at a million requests per minute. 01 · Intro…
A complete, beginner-to-production system design walkthrough for a bulk payroll payment processing system that pays 50,000 employees the correct amount, exactly once, every pay period — using idempotency keys, the Saga pattern, the outbox pattern, chunk-level checkpointing, and banking-rail reconciliation at platform scale.
Designing a “Buy Online, Pick Up In Store” (BOPIS) System A complete system design walkthrough for coordinating real-time inventory between an online marketplace and thousands of physical store locations — built to survive a million requests a minute. 01 · Intro & History02 · Problem03 · Core Concepts04 · Architecture05…
Designing a Multi-Touch Affiliate & Referral Attribution System How marketplaces like Amazon, Flipkart, Uber, and Airbnb track every click a referrer generates, follow a customer across days or weeks of browsing, and fairly decide who gets paid when a sale finally happens — explained plainly enough for a first-week engineer,…
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…
Designing a Buy Now, Pay Later (BNPL) System with Real-Time Credit Decisioning A complete, from-first-principles walkthrough of how to architect a marketplace financing feature that lets a customer split a purchase into instalments, with a credit decision returned in real time, at checkout, without breaking the shopping experience. 01 ·…
Designing a Money Laundering Pattern Detection System A complete, beginner-to-production system design walkthrough: how to catch suspicious aggregate patterns hidden across millions of individually legitimate-looking transactions, in near real time, at massive scale — using streaming aggregation, graph-based network analysis, and machine learning working together. 01 · Intro & History02…
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 ·…