System Design Sheet

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Complete HLD question bank for full coverage, and long-term mastery.

Overall progress

0/111 solved

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easy0/11

medium0/54

hard0/46

0/111

Solved

CategoryCompanyDifficultyStatus

Web Services

0/3 solved

Status	Star	Problem	Difficulty	Notes
		Design a URL Shortener (TinyURL / Bit.ly) Asked by:GoogleMetaAmazon+3 more	easy
		Design Pastebin Asked by:GoogleDropboxAmazon+1 more	easy
		Design an Online Judge System (Leetcode) Asked by:LeetCodeHackerRankGoogle+1 more	hard

Infrastructure

0/19 solved

Status	Star	Problem	Difficulty	Notes
		Design an API Rate Limiter Asked by:StripeGoogleAmazon+3 more	easy
		Design a Unique ID Generator (Twitter Snowflake) Asked by:TwitterMetaMicrosoft+1 more	easy
		Design a Notification System (Push, Email, SMS) Asked by:AppleMetaAmazon+2 more	easy
		Design a Load Balancer Asked by:GoogleAWSMicrosoft+2 more	easy
		Design a Content Delivery Network (CDN) Asked by:NetflixCloudflareAmazon+1 more	medium
		Design a Distributed Cache (Redis / Memcached) Asked by:TwitterMetaRedisLabs+1 more	medium
		Design a Distributed Job Scheduler (Quartz / Airflow) Asked by:GoogleNetflixAirbnb+1 more	medium
		Design a Distributed Lock Manager Asked by:UberGoogleAmazon+1 more	medium
		Design a Distributed Worker Queue (RabbitMQ / SQS) Asked by:AmazonMicrosoftUber+1 more	medium
		Design a Distributed Message Broker (Kafka-style) Asked by:LinkedInConfluentUber+1 more	medium
		Design an Event Sourcing System Asked by:StripeSquareUber+1 more	medium
		Design a Circuit Breaker Asked by:NetflixMicrosoftGoogle+1 more	medium
		Design a Service Discovery System Asked by:HashiCorpNetflixAWS+1 more	medium
		Design a Backup and Disaster Recovery System Asked by:AWSGoogleMicrosoft+1 more	medium
		Design a Distributed Consensus System (Raft / Paxos) Asked by:GoogleCoreOSHashiCorp+1 more	hard
		Design a P2P File Transfer System (like BitTorrent) Asked by:BitTorrentNetflixSpotify+1 more	hard
		Design a Workflow Orchestration Engine (like Temporal/Cadence) Asked by:TemporalUberNetflix+1 more	hard
		Design a Distributed Coordination Service (ZooKeeper) Asked by:GoogleYahooTwitter+1 more	hard
		Design an API Gateway (Kong / Envoy) Asked by:KongStripeNetflix+1 more	hard

Storage

0/6 solved

Status	Star	Problem	Difficulty	Notes
		Design a Key-Value Store Asked by:AmazonGoogleMeta+1 more	medium
		Design Dropbox / Google Drive (File Storage + Sync) Asked by:DropboxGoogleMicrosoft+1 more	medium
		Design a Social Graph Store Asked by:MetaLinkedInTwitter+1 more	hard
		Design a Time-Series Database Asked by:InfluxDataDatadogPrometheus+1 more	hard
		Design a Blob Storage System (like S3) Asked by:AWSGoogleMicrosoft+1 more	hard
		Design a Relational Database (PostgreSQL) Asked by:GoogleAmazonMicrosoft+1 more	hard

Messaging

0/3 solved

Status	Star	Problem	Difficulty	Notes
		Design a Real-Time Chat Application (WhatsApp / Slack) Asked by:MetaSlackMicrosoft+1 more	medium
		Design a User Presence System Asked by:SlackWhatsAppMicrosoft+1 more	medium
		Design an Email Service (like Gmail) Asked by:GoogleMicrosoftYahoo+1 more	hard

Search

0/3 solved

Status	Star	Problem	Difficulty	Notes
		Design Google Typeahead / Autocomplete Asked by:GoogleMicrosoftAmazon+1 more	easy
		Design a Search Engine (Google) Asked by:GoogleMicrosoftAmazon	medium
		Design Quora (Q&A Platform) Asked by:QuoraPinterestGoogle+1 more	medium

Realtime Systems

0/6 solved

Status	Star	Problem	Difficulty	Notes
		Design Live Likes & Reactions Asked by:MetaByteDanceTwitter+1 more	medium
		Design a Shared Calendar System (like Google Calendar) Asked by:GoogleMicrosoftApple	medium
		Design a Live Comments System (like Facebook Live / YouTube Live) Asked by:MetaGoogleTwitch+1 more	hard
		Design Google Docs (Real-Time Collaborative Editing) Asked by:GoogleMicrosoftAtlassian+1 more	hard
		Design a Video Conferencing System (like Zoom) Asked by:ZoomMicrosoftGoogle+1 more	hard
		Design a Multiplayer Game Backend Asked by:Epic GamesRobloxRiot Games+1 more	hard

Social

0/8 solved

Status	Star	Problem	Difficulty	Notes
		Design a Timeline and Tweet Service (Twitter) Asked by:TwitterMetaLinkedIn+1 more	easy
		Design Instagram (Photo Sharing + Social Features) Asked by:MetaPinterestSnap+1 more	easy
		Design a News Feed System (Facebook / Instagram) Asked by:MetaTwitterLinkedIn+1 more	medium
		Design a Threaded Discussion Forum (Reddit) Asked by:RedditMetaGoogle+1 more	medium
		Design Ephemeral Stories (Instagram Stories) Asked by:MetaSnapLinkedIn+1 more	medium
		Design a Follower/Following System Asked by:MetaTwitterLinkedIn+1 more	medium
		Design a Mentions & Tagging System Asked by:MetaTwitterSlack+1 more	medium
		Design TikTok (Short Video Platform) Asked by:ByteDanceSnapMeta+1 more	hard

Media Streaming

0/7 solved

Status	Star	Problem	Difficulty	Notes
		Design a Music Streaming Service (Spotify) Asked by:SpotifyAppleAmazon+1 more	easy
		Design a Video Streaming Platform (YouTube / Netflix) Asked by:NetflixGoogleAmazon+1 more	medium
		Design an Image Processing Pipeline Asked by:PinterestSnapInstagram+1 more	medium
		Design a Thumbnail Generation Service Asked by:PinterestNetflixDropbox+1 more	medium
		Design a Podcast Delivery Platform Asked by:SpotifyAppleGoogle	medium
		Design a Video Transcoding Pipeline Asked by:NetflixGoogleTwitch+1 more	hard
		Design a Live Streaming Platform like Twitch Asked by:AmazonGoogleMeta+1 more	hard

Commerce Marketplace

0/13 solved

Status	Star	Problem	Difficulty	Notes
		Design a Food Delivery Platform (DoorDash / Zomato) Asked by:DoorDashUberInstacart+1 more	medium
		Design an E-Commerce Platform (Amazon / Flipkart) Asked by:AmazonWalmarteBay+1 more	medium
		Design a Ticketing System (BookMyShow / TicketMaster) Asked by:TicketmasterAmazonGoogle	medium
		Design a Bike Sharing System like Citi Bike Asked by:UberLyftLime	medium
		Design a Shopping Cart System Asked by:AmazonWalmartShopify+1 more	medium
		Design an Order Management System Asked by:AmazonWalmartShopify+1 more	medium
		Design a Review and Rating System Asked by:YelpAmazonGoogle+1 more	medium
		Design a Price Comparison Engine Asked by:GoogleAmazonPayPal	medium
		Design a Coupon and Discount Engine Asked by:AmazonWalmartPayPal+1 more	medium
		Design a Hotel Booking System Asked by:Booking.comExpediaAirbnb+1 more	medium
		Design an Inventory Management System Asked by:AmazonWalmartShopify+1 more	hard
		Design a Flash Sale System Asked by:AlibabaAmazonFlipkart+1 more	hard
		Design a Surge Pricing System like Uber or Lyft Asked by:UberLyftBolt+1 more	hard

Fintech Payments

0/6 solved

Status	Star	Problem	Difficulty	Notes
		Design a Payment Gateway (Handling ACID Transactions) Asked by:StripePayPalSquare+2 more	medium
		Design a Multi-Currency Payment System Asked by:StripePayPalWise+1 more	medium
		Design a Digital Wallet System Asked by:PayPalBlockGoogle+1 more	hard
		Design a Stock Exchange Matching Engine Asked by:NasdaqNYSERobinhood+2 more	hard
		Design a Distributed Banking Ledger System Asked by:StripeBlockPayPal+2 more	hard
		Design a Cryptocurrency Exchange Asked by:CoinbaseBinanceRobinhood+1 more	hard

Geo Location

0/8 solved

Status	Star	Problem	Difficulty	Notes
		Design a Proximity Server (Yelp / Nearby Friends) Asked by:UberLyftGoogle+2 more	easy
		Design a Ride-Hailing Service (Uber) Asked by:UberLyftGrab+2 more	medium
		Design a Geofencing Service Asked by:UberLyftDoorDash+1 more	medium
		Design Foursquare (Check-ins and Recommendations) Asked by:AirbnbUberFoursquare+1 more	medium
		Design a Real-time Vehicle Tracking System Asked by:UberLyftGrab+1 more	medium
		Design Tinder (Matching System) Asked by:Match GroupTinderBumble+1 more	hard
		Design a Map Rendering and Navigation System like Google Maps Asked by:GoogleAppleUber+1 more	hard
		Design an ETA Calculation Service Asked by:UberLyftGoogle+1 more	hard

Data Analytics

0/10 solved

Status	Star	Problem	Difficulty	Notes
		Design a Web Crawler (Googlebot) Asked by:GoogleMicrosoftYahoo	medium
		Design Top K Rankings System (App Store / Amazon Bestsellers) Asked by:AppleAmazonGoogle+2 more	medium
		Design a Distributed Stream Processing System (Apache Flink) Asked by:NetflixUberLinkedIn+1 more	medium
		Design a Trending Topics System Asked by:TwitterByteDanceMeta+1 more	medium
		Design Top K Most Shared Articles Asked by:TwitterMetaLinkedIn+1 more	medium
		Design a Leaderboard System Asked by:SonyMicrosoftApple+1 more	medium
		Design a User Analytics Pipeline (like Google Analytics) Asked by:GoogleMixpanelAmplitude+1 more	hard
		Design Like Count for High Profile Users Asked by:TwitterMetaByteDance+1 more	hard
		Design a Real-Time Bidding System (Ad Tech) Asked by:GoogleTradeDeskMeta+1 more	hard
		Design a Change Data Capture (CDC) Pipeline Asked by:NetflixDebeziumStripe+1 more	hard

Observability Devops

0/7 solved

Status	Star	Problem	Difficulty	Notes
		Design a Distributed Tracing System (like Jaeger / Zipkin) Asked by:UberGoogleNetflix+1 more	medium
		Design an On-Call Escalation System (like PagerDuty / OpsGenie) Asked by:PagerDutyAtlassianMicrosoft+1 more	medium
		Design a Distributed Metrics Aggregation System Asked by:DatadogUberNetflix+1 more	medium
		Design a Real-time Dashboard and Metrics System Asked by:DatadogUberGrafana+1 more	medium
		Design a Feature Flag System Asked by:LaunchDarklyNetflixMeta+1 more	medium
		Design a Log Aggregation and Search System (like Splunk / ELK) Asked by:SplunkElasticDatadog+1 more	hard
		Design a Code Hosting Platform (GitHub) Asked by:GitHubGitLabAtlassian+1 more	hard

Security Trust

0/2 solved

Status	Star	Problem	Difficulty	Notes
		Design an Authentication and Authorization System (OAuth 2.0/SSO) Asked by:OktaMicrosoftGoogle+1 more	hard
		Design a Content Moderation System Asked by:MetaByteDanceGoogle+1 more	hard

Machine Learning

0/7 solved

Status	Star	Problem	Difficulty	Notes
		Design a Recommendation System (Netflix / TikTok Style) Asked by:NetflixByteDanceGoogle+1 more	hard
		Design a Video Recommendation Engine Asked by:NetflixGoogleByteDance	hard
		Design a Fraud Detection System Asked by:StripePayPalCoinbase+2 more	hard
		Design an A/B Testing and Experimentation Platform Asked by:NetflixMetaOptimizely+1 more	hard
		Design an Ad Click Prediction System Asked by:GoogleMetaTradeDesk+1 more	hard
		Design an ML Feature Store Asked by:UberFeastTecton+2 more	hard
		Design a Search Ranking System (Learning to Rank) Asked by:GoogleMicrosoftAmazon+1 more	hard

Ai Applied Systems

0/3 solved

Status	Star	Problem	Difficulty	Notes
		Design an LLM Chat Application (ChatGPT) Asked by:OpenAIAnthropicGoogle+1 more	hard
		Design an AI Coding Assistant (Cursor / Claude Code) Asked by:CursorAnthropicCognition+2 more	hard
		Design a Document Q&A Platform (RAG System) Asked by:OpenAICoherePinecone+1 more	hard