RADIO step by step
Comes up in: Frontend system design
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- Requirements (5–8 min: users, features, scale, devices, constraints, out-of-scope)
- Architecture (components, data flow, rendering strategy)
- Data model (entities, client stores, normalisation)
- Interface (API shape, events, component props)
- Optimisations (performance, network, a11y, i18n, security, offline)
- time management and signposting
Words you will know
What you will practise
- RADIO outline for a "like button" (worked) and a "photo feed" (faded)
Interview questions this answers
- How do you decide on a rendering strategy for a new product?
- Design a search autocomplete for an e-commerce site.
- Design a news feed like a social network's home page.
- How would you build a photo-sharing app's upload flow?
- Design a commenting widget that other websites can embed.
- Design an e-commerce product listing page with filters that is fast and SEO-friendly.
- For the news feed: how do you handle 10x traffic on a big news day?
- How would you measure the quality of search suggestions?
- How does your e-commerce design behave on a slow 3G connection?
- What happens to a half-uploaded photo when the network drops?
- How do you make an infinite feed accessible?
- Design a chat application frontend. How do you handle offline messages and ordering?
- Design a collaborative editor like a shared document. How do you resolve concurrent edits?
- Design an in-app notification system with unread counts across tabs.
- Design a kanban tool used by many people at once.
- Design the client of a video-calling app.
- How do you show presence and typing indicators without flooding the server?
- What happens when a chat user is offline for a week?
- How do you keep notification counts correct across devices?
- How do you test real-time features?
- Design an analytics dashboard with many charts and real-time data.
- Design a web spreadsheet. How do you render a million cells and recalculate formulas?
- Design a calendar with recurring events across time zones.
- How do you safely render HTML emails?
- Design a file upload system that survives network drops.
- How do you keep a dashboard fast when every widget fetches data?
- How do you support undo in a spreadsheet with formulas?
- How do you show a calendar correctly to people in different time zones?
- Design a video streaming player for web.
- Design a movie seat booking page. How do you prevent two users booking the same seat?
- Design a hotel search results page where results arrive slowly from many suppliers.
- Design the frontend of a ride-hailing app's live tracking screen.
- Design a checkout that supports cards and UPI. How do you handle a payment whose status is unknown?
- What metrics tell you the video player gives a good experience?
- How does the seat map work for screen-reader users?
- How do you handle a price that changes between search and checkout?
- Design a component library used by 20 teams.
- Design an AI assistant side panel for a SaaS product.
- Design a platform that lets 10 teams ship parts of one web app independently.