Amazon System Design Questions

Design an Amazon Locker Service

Design an Amazon Locker system: self-service package locker stations with compartments of different sizes. When an order is shipped to a locker, the system assigns a compartment of appropriate size, the courier deposits the…

Also reported as: Design a multi-size storage locker system

Design a Scalable News Feed

Design the home feed of a social network like Instagram or Twitter. Users create posts (text, photos, video), follow other users, and open a personalized feed of recent posts from people they follow, possibly mixed with global or…

Also reported as: Design a scalable image-based social network

Design a Library Management System (API and Schema)

Design a multi-branch library management system: catalog search, members borrowing and returning copies, reservations/holds with a waitlist, due dates and fines, and branch-level availability of each copy. Discuss the relational…

Also reported as: Design a Multi-Branch Library Lending System

Accept Notification Bursts With Low Latency

Design a multi-channel notification service (push, email, SMS, in-app) that other services call to notify users. It must accept sudden bursts of millions of notifications with low acknowledgement latency, persist them durably,…

Design a Product Image Upload Pipeline for Sellers

Design a service that accepts large user uploads (files or product images, GBs in size), validates them, processes them asynchronously (virus scan, analysis, thumbnails, moderation), and makes results or approved assets available…

Design Faceted Product Search at Large Scale

Design product search for a large e-commerce catalog that supports free-text queries combined with filters and facets (price range, brand, category and nested subcategories, rating), facet counts, sorting, and deterministic…

Design a Scalable Metrics Monitoring System

Design an internal metrics monitoring platform like Datadog or Prometheus. Agents on hosts and services emit metrics (counters, gauges, histograms with tags); the system ingests millions of data points per second, stores them as…

Architect an AI Chatbot for Enterprise Users

Design a ChatGPT-style conversational AI product. Users send a message and receive a streamed response from a model; conversations persist and can be resumed on any device; the service must stay highly available despite limited,…

High Availability and Failover for a Primary-Replica Database

Design high availability for a primary-replica relational database. Explain replication modes (synchronous vs asynchronous) and their data-loss implications, how primary failure is detected, how a replica is safely promoted…

Object-Oriented Design: Snake Game

Design the Snake game with object-oriented design: a grid board, a snake that moves in a direction and grows when it eats food, food spawning at random free cells, and the game ending on collision with a wall or itself. Discuss…

Design a Perishable-Goods Inventory and Location Tracking System

Design a system that tracks inventory and location of perishable goods (with expiry dates) across a distributed retail network of warehouses, trucks and stores. Support real-time stock levels by location, first-expiring-first-out…

Design a Core Dump Collection and Analysis System

Design a system that collects core dumps from crashing processes across a large fleet of hosts, stores them, and helps engineers analyze them. Dumps can be large (GBs) and crashes can spike during a bad deployment. Discuss…

Design a Scalable and Polite Web Crawler

Design a distributed web crawler that starts from seed URLs and crawls about 10 billion pages (or all images reachable from given root URLs), with periodic recrawls. It must avoid fetching the same URL twice, obey robots.txt and…

Design a Distributed Cron Job Scheduler

Design a distributed job scheduler that runs user-defined jobs at a specified time (one-time) or on a recurring cron schedule, at a scale of millions of jobs per day. Requirements: jobs fire close to their scheduled time, each…

Design Music Search, Playlists, and Playback Controls

Design a music playlist service (and optionally music search and playback controls). Users create playlists, add and remove tracks (duplicates allowed), reorder items, and share collaborative playlists that several users edit…

Design a Log Collection System

Design a centralized logging platform (like ELK, Splunk or Datadog Logs) for a company with thousands of services and hosts. Agents collect logs from applications and infrastructure, ship them reliably under backpressure, and the…

Design Human Avoidance for Warehouse Robots

Design the human-avoidance subsystem for autonomous warehouse robots: fuse sensor data (lidar, cameras, proximity sensors) to detect humans, predict their motion, and adjust the robot's path or stop within strict latency and…

Design a High-Availability Load Balancer

Design a highly available software load balancer at layer 4 or layer 7 for HTTP/HTTPS traffic. Cover backend selection algorithms (round robin, least connections, consistent hashing), health checks, connection lifecycle and…

Design a Ride-Hailing Matching System

Design the core of a ride-hailing platform like Uber. Riders request a ride from their location; the system finds nearby available drivers, dispatches the request, and tracks the trip in real time. Drivers report their location…

Design a Multi-Provider Financial Dashboard

Design a personal finance dashboard that shows bank account balances, stock holdings, cryptocurrency holdings and derived portfolio metrics. Data comes from multiple external providers with different schemas, update frequencies,…

Design a cloud database write path and recovery

Design the core components of a relational database (like MySQL or PostgreSQL), or the write path and crash recovery of a cloud-native database that separates compute from durable storage (like Aurora). Cover the storage engine…

Design a large-scale temperature sensor system

Design a telemetry pipeline for a very large fleet of devices or sensors (e.g., millions of temperature sensors, GPUs, or IoT devices each reporting every few seconds). Devices may be offline and upload batched, late-arriving…

Review an existing architecture for risks

You are given an existing architecture or design document (for example Client -> DNS -> Load Balancer -> Application Service -> Database, plus a call to a third-party API) that contains omissions and unsafe assumptions. Review…

Design multi-tenant ingestion and processing platform

Design a multi-tenant platform that ingests data from many customers (tenants) and runs processing pipelines on it. Requirements: tenant isolation (security and noisy-neighbor protection), per-tenant quotas and fair scheduling,…

Design globally consistent metadata service

Design a metadata service that must be globally consistent (linearizable), for example storing bucket or namespace metadata for a global storage system accessed from many regions. Discuss partitioning, replication across regions,…

Design an Offline Multi-Device E-Book Reader

Design an e-book reader service (like Kindle): users buy and download books, read offline on multiple devices, and have reading position, bookmarks, highlights and notes synced across devices. Discuss the APIs, database schema,…

Design a package installer with dependencies

Design a package installer/manager (like apt or npm): given a package to install, resolve its dependencies transitively with version constraints, detect missing packages and conflicts, compute a valid install order (topological…

Design an S3-like object storage service

Design a cloud object storage service like Amazon S3 where clients upload, download and delete objects (up to many GB) organized in buckets. Requirements: very high durability (11 nines), high availability, multipart and…

Design an Online Minesweeper Platform

Design an online Minesweeper platform: users start games at various difficulty levels, reveal and flag cells with low latency, resume games later, and compete on leaderboards for best times. Discuss where game state lives and who…