Pattern series
State Machine + Idempotent Transitions
8 System Design questions share this exact tag. Use the closely related series below for a fuller drill.
- 01Preview
Auction (eBay)
Design an eBay-style auction system — bidders compete on live listings under heavy contention near closing time, and the system must never accept a lo...
eBay - 02Preview
Chat App
Design the client-side architecture of a WhatsApp-style mobile messenger — connection handling, message state, offline storage, and encryption all hav...
Discord - 03Preview
Hotel Reservation
Design a single-chain hotel reservation engine — travelers search date-range availability across properties, place a hold, and confirm a booking witho...
Practice bank - 04Preview
Netflix
Design Netflix’s video delivery system — stream a licensed, curated catalog to tens of millions of concurrent viewers worldwide with minimal buffering...
Netflix - 05Preview
Robinhood (Stock Trading)
Design a retail stock trading platform like Robinhood that lets millions of users place buy/sell orders, tracks cash and positions with regulatory-gra...
Robinhood - 06Preview
Real-time Voice AI Agent
Design a real-time voice AI agent platform for phone support and voice assistants: the complete loop from the user speaking to the agent speaking back...
Practice bank - 07Preview
Stock Exchange
Design the core trading system of a stock exchange: accept orders into a central limit order book, match at price-time priority, and when your own boo...
Practice bank - 08Preview
Food Delivery Marketplace
Design a DoorDash-style food delivery marketplace connecting consumers, Dashers, and merchants.
Uber