•SYSTEM DESIGN
Netflix System Design Questions
Every system design problem candidates reported at Netflix between September 2025 and September 2026, most-asked first. Each one links to a full solution.
Problems
9
Candidate reports
20
Asked more than once
3
start here
Question type
9 HLD
Design a Distributed Frequency-Capping Service
Design a frequency-capping service for an advertising platform. Advertisers set caps such as 'a user may see this ad, campaign or line item at most N times per rolling 24 hours or 7 days'. On each ad request (tens to hundreds of…
Also worded as: Design Ad Frequency and Order Tracking · Design Rolling-Window Ad Frequency Capping +3
Model ads demand data for reporting
Design the data model for an advertising platform: advertisers/accounts, campaigns with budgets and flight dates, ad groups or line items, creatives and assets, targeting criteria, and delivery and performance events. Cover the…
Also worded as: Model data for an ads platform · Design an ads data model
Design Publisher Configuration Rules
Design a configuration system for the supply side of an ad platform: publishers own many sites, apps and placements, and each needs custom rules (allowed ad categories, floor prices, frequency limits) with inheritance from…
Also worded as: Design config rollout and click aggregation
Design a Scheduler for ML Training and Batch Inference Jobs
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 a File Backup System
Design a file (or photo) storage and sync service like Dropbox, Google Drive or iCloud Photos. Users upload files from one device and see them on all devices; they can share files and folders, keep versions, and work offline with…
Design an Ad Pacing System
Design an ad pacing system for a large video advertising platform. Advertisers create campaigns with budgets, start and end dates, targeting, and delivery goals (impressions or spend); the system must spread delivery smoothly…
Design homepage viewport rendering with deduplication
Design how a streaming app's homepage (like Netflix) renders rows of titles: fetch only the rows and items visible in the viewport (lazy loading as the user scrolls), and deduplicate titles so the same show does not appear in…
Design an ads audience targeting system
Design an audience targeting system for an ads platform. Advertisers define audiences (segments by demographics, interests, lists of user IDs, lookalikes), and at ad-serving time the system must decide within milliseconds which…
Design config rollout and click aggregation
Design an ad click and impression aggregation system. Ingest a high-volume stream of ad events ({ad_id, campaign_id, user_id, event_type, timestamp}, billions per day) and provide aggregated metrics (clicks, impressions, CTR per…
Duplicate reports of the same problem are merged and counted.
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What system design questions does Netflix ask?
Candidates reported 9 distinct system design problems at Netflix between September 2025 and September 2026, including Design a Distributed Frequency-Capping Service, Model ads demand data for reporting, Design Publisher Configuration Rules.
How to prepare for Netflix system design interview?
Start with the Netflix problems reported most often, work through each full solution, then practice explaining a design end to end under time pressure in a mock interview.
What is the difference between HLD and LLD at Netflix?
HLD (High-Level Design) focuses on system architecture, scalability, and component interactions. LLD (Low-Level Design) dives into class diagrams, API contracts, and database schemas. Netflix tests both.