Design Netflix homepage rows with no repeats
PremiumFrontend systemMedium
- Deduplication
- List virtualisation
- Lazy loading
Quick answer
This frontend system interview question asks you to design Netflix homepage rows with no repeats. Aim for a design that loads fast, stays responsive and is easy to maintain, then explain components, state, data fetching and trade-offs. Interviewers want to see how you structure the interface, manage state and keep the experience fast.
The problem
Design the browser side of a Netflix-style homepage: many horizontal rows of titles that load lazily, scroll sideways and come in a personalised order. The hard part is that no title may repeat on screen while rows keep arriving, and the page must stay smooth on desktops and TVs.
The backend already ranks rows and titles for each profile. You build what runs on the device: the row list, deduplication, virtualisation, caching and keyboard or remote navigation.
What must the system do?
- No repeats on screen: Apply the rule above as rows and tiles load, so a title is never visible twice and placed tiles never swap.
- Lazy rows: Show the first rows fast and load more rows as the user scrolls down, keeping the server order.
How well must it do it?
- Smooth scrolling: Keep 60 fps while scrolling in both directions, so each frame has about 16.7 ms of work.
- Fast first screen: Largest Contentful Paint within 2.5 s on desktop broadband; the first screen needs no client fetch.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Deduplication
- List virtualisation
- Lazy loading
- Spatial navigation
- IntersectionObserver
- Roving tabindex
How you’ll practise
- Requirements
- Components
- State and data
- Network and caching
- Performance and accessibility
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any frontend system design round.
- Starts from the user flows and the screens
- Splits the interface into clear components
- Decides where state lives and how it stays in sync
- Plans data fetching, caching and loading states
- Covers performance, accessibility and error states
- Explains how the design holds up on slow networks and small screens
Questions people ask about this interview question
- Which design type is this question?
- It is a frontend system question. You design Netflix homepage rows with no repeats and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the main user flows, the screens and the data each one needs. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
Related questions
Updated · Written by the SevyDevy team