Zoom system design interview questions

One question on this site is reported in Zoom software engineer interviews. Each has a full reference design (requirements, back-of-envelope numbers, components, user flows and deep dives with interviewer follow-ups). Each one can be walked through turn by turn and then sat as a mock. Patterns covered: webrtc, sfu, real-time-media, congestion-control, multi-region.

Attribution comes from public interview guides and candidate reports, not from Zoom. It indicates where a question has been asked, nothing more.

hard

Design Zoom

Real-time audio, video and screen share for 2 to 1,000 people per meeting, 300 M participants a day, under 150 ms mouth to ear.

webrtcsfureal-time-mediacongestion-controlmulti-region

Walkthrough Mock interviewPro Read the reference

How to prepare for the Zoom system design interview

Large-company loops run 45 to 60 minutes, expect numbers, and spend most of the time on deep dives. Walk through a question to see how a strong candidate paces the hour, sit the same question as a mock until you can produce the requirements, the estimates and the design without looking, then read the interview framework guide for how to structure the hour. The other questions on the site teach patterns that show up in Zoom interviews under different names.

Design a URL Shortenerkey-generation · caching · cdn
Design Slackreal-time · websockets · fan-out
Design a Payment Systemconsistency · idempotency · ledger
Design a News Feedfan-out · ranking · caching
Design YouTubetranscoding · cdn · adaptive-bitrate
Design Google Mapsgeospatial · routing · graphs
Design a Matchmaking Systemqueues · scheduling · latency
Design Ubergeospatial · matching · streaming
Design a Notification Systemfan-out · multi-channel · idempotency
Design Google Docscrdt · operational-transform · websockets
Design an LLM Inference Servicegpu-batching · streaming · scheduling
Design ChatGPTstreaming · tool-calling · context-management
Design a Distributed Cacheconsistent-hashing · eviction · replication
Design a Web Crawlerfrontier · politeness · dedupe
Design a Rate Limiteralgorithms · counters · redis
Design Dropboxchunking · dedupe · sync
Design Ticketmasterinventory · reservations · locking
Design Search Autocompletetries · ranking · caching
Design an Ad Click Aggregatorstream-processing · windowing · exactly-once
Design a Distributed Job Schedulerscheduling · leases · idempotency
Design a Stock Exchangeorder-book · determinism · event-sourcing
Design a Project-to-Contractor Matching Systemrecommendations · ranking · marketplace
Design Instagrammedia-pipeline · object-storage · fan-out
Design WhatsApppersistent-connections · store-and-forward · end-to-end-encryption
Design Netflixcdn · proactive-caching · adaptive-bitrate
Design Yelpgeospatial-index · search · ranking
Design a Real-Time Leaderboardsorted-sets · ranking · sharding
Design a Distributed Key-Value Storeconsistent-hashing · quorum-replication · conflict-resolution
Design a Unique ID Generatorid-generation · clocks · leases
Design LeetCodesandboxing · job-queue · untrusted-code
Design Airbnbavailability-search · inventory · double-booking
Design a Distributed Message Queueappend-only-log · partitioning · replication
Design a Metrics and Monitoring Systemtime-series · compression · cardinality
Design Tindergeo-sharding · recommendations · bloom-filters
Design Redditcomment-trees · voting · ranking
Design DoorDashstate-machine · dispatch · eta-prediction
Design AWS Step Functionsworkflow-orchestration · event-sourcing · durable-timers
Design Apache Airflowworkflow-orchestration · dag-scheduling · backfills
Design Zapierworkflow-orchestration · polling · webhooks
Design an Online Auctioncontention · compare-and-set · durable-timers
Design Live Commentsbroadcast · pub-sub · sse
Design a Top-K Heavy Hitters Serviceheavy-hitters · count-min-sketch · sliding-windows
Design Google Searchinverted-index · scatter-gather · tail-latency
Design Spotifyprefetching · licensing · offline
Design Gmailsmtp-ingress · spam-filtering · per-user-sharding
Design Amazonshopping-cart · inventory · caching
Design a Large File Distribution Systempeer-to-peer · chunking · bandwidth
Design a Recommendation Systemrecommendations · ranking · vector-search
Design a Distributed Lock Serviceconsensus · leases · fencing-tokens
Design an Object Storage Serviceerasure-coding · range-partitioning · durability
Design Google Calendarrecurrence · time-zones · fan-out
Design a Code Deployment Systemdeployment · canary · reconciliation
Design a Distributed Logging Systemlog-aggregation · inverted-index · tiered-storage
Design Twitchlive-video · low-latency · transcoding
Design a Price Trackeradaptive-scheduling · change-detection · time-series
Design Stravageospatial · async-pipeline · spatial-matching
Design Post Searchsearch · real-time · privacy
Design Figmamultiplayer · last-writer-wins · websockets
Design a Load Balancerload-balancing · networking · consistent-hashing
Design a RAG Systemrag · vector-search · hybrid-search
Design a CDNcdn · anycast · tiered-cache
Design an API Gatewayapi-gateway · authentication · control-plane
Design a Social Graphgraph · sharding · in-memory
Design an Ad Serving Systemauctions · budget-pacing · ranking
Design GitHubgit · replication · quorum
Design Venmoledger · sharding · hot-keys
Design a Multiplayer Game Backendreal-time · udp · game-servers
Design TikTokshort-video · prefetch · session-ranking
Design Google Newsclustering · ingestion · ranking
Design an A/B Testing Platformexperimentation · hashing · statistics
Design GitHub Copilotlatency-budget · cancellation · prefix-caching
Design Nearby Friendsreal-time · pub-sub · fan-out
Design a Fraud Detection Systemfraud · feature-store · stream-processing
Design Pastebinobject-storage · expiry · caching
Design a Webhook Delivery Systemwebhooks · retries · isolation
Design Pinterestrandom-walks · visual-search · deduplication
Design a Vector Databasevector-search · ann-indexes · quantisation
Design a Content Moderation Systemmoderation · perceptual-hashing · review-queues
Design Robinhoodmarket-data · order-management · ledger
Design a Flight Booking Systemfan-out · caching · saga
Design a Container Orchestratorscheduling · reconciliation · consensus
Design Discordreal-time · fan-out · actors

Questions people ask about the Zoom system design interview

What system design questions does Zoom ask?

The question reported in Zoom system design interviews is Zoom. It tests webrtc, sfu, real time media, congestion control and multi region. The reports come from public interview guides and candidate accounts, not from Zoom, so practise the patterns rather than memorising one list.

How do I prepare for the Zoom system design interview?

Practise the questions reported there out loud, under a 45-minute clock: requirements with numbers first, then estimates, a high-level design, and deep dives into the two or three hardest parts. Start with Zoom: watch a strong candidate answer it turn by turn, then sit it yourself. Then cover the patterns the round leans on (webrtc, sfu, real time media and congestion control) with one more question each.