A deep, interview-focused walkthrough of how to design a marketplace customer service chatbot that answers “Where is my order?”, “Is this in stock?”, and “What is my account balance?” correctly, in under two seconds, at millions of requests per day, with strict per-customer authorization on every single live data fetch.

System Design · Professional Networking Designing a Job Recommendation System for a Professional Networking Platform How do platforms like LinkedIn quietly figure out that you, specifically, should see this job and not that one — out of millions of postings, updated every second, for hundreds of millions of people? We…

Designing a Live-Streaming System That Survives a Mid-Broadcast Viral Spike A production-grade blueprint for scaling a single live stream from a few hundred viewers to millions within minutes — without buffering, without falling behind, and without the broadcaster ever noticing. 01 · Intro & History02 · Problem03 · Core Concepts04…

Designing a Live Shopping Platform with Real-Time Inventory A complete, ground-up architecture for a system where a creator sells products live on video, thousands of viewers watch and chat in real time, and every purchase must update inventory instantly and correctly — even when ten thousand people click “Buy” on…

Designing Live Commenting & Reactions for Millions of Concurrent Viewers A single tap of a heart. A one-line comment during the final seconds of a match. Multiply that by ten million people watching the same moment at once, and you have one of the hardest real-time fan-out problems in distributed…

A complete, from-scratch walkthrough of how a marketplace platform lets customers earn points from purchases and redeem them across a wide range of rewards — covering ledger architecture, real-time balance tracking, redemption orchestration, fraud prevention, scaling, and the production patterns behind it.

A complete, ground-up walkthrough of how to build a real-time score and stats system that can serve tens of millions of fans watching the same match at the same second — covering architecture, data flow, databases, caching, scaling, reliability, and the trade-offs behind every decision.

Designing a Unified Feed for Text Posts and Long-Form Video A complete, interview-ready walkthrough of building one feed architecture that can seamlessly serve short text posts and long-form video content — from ingestion and transcoding to ranking, fan-out, caching, and global delivery at millions of requests per second. 01 ·…

Designing an Influencer Marketing Attribution Platform How do you track a sale that happens on Shopify, Amazon, and a brand’s own website — and prove, with confidence, that it happened because of a video a creator posted three days ago on Instagram? This deep dive builds that system from first…

Designing a Hybrid Marketplace: Instant Digital Delivery + Physical Shipment in One Checkout A production-grade architecture for a marketplace where a single cart, a single checkout flow, and a single order can contain a software license that must be delivered in milliseconds and a physical product that must travel through…