RADIO Framework Guide

Welcome to the RADIO Framework Guide—a structured approach to system design interviews and architecture decisions for front-end applications.

About RADIO

The RADIO framework was created by Yangshun Tay, a former Staff Engineer at Meta (Facebook) and the creator of GreatFrontEnd, a comprehensive platform for front-end engineering interview preparation.

This framework provides a systematic approach to front-end system design, helping engineers structure their thinking and demonstrate depth in technical interviews. We've adapted and expanded RADIO to map to the patterns and strategies in this documentation.

What is RADIO?

RADIO is a mnemonic framework that helps you systematically approach system design questions:

• R - Requirements: Understand the problem, constraints, and goals
• A - Architecture: Design the high-level system structure
• D - Data Model: Define how data flows and is stored
• I - Interface: Design the user interface and interactions
• O - Optimizations: Improve performance, scalability, and reliability

Why RADIO?

System design interviews can be overwhelming. RADIO provides a structured mental model to:

1. Avoid missing critical aspects - Each letter reminds you of key considerations
2. Think systematically - Follow a logical flow from requirements to optimizations
3. Demonstrate depth - Show you understand trade-offs at each layer
4. Stay organized - Present your solution clearly and comprehensively

How to Use This Guide

This guide maps all the patterns and strategies in this documentation to the RADIO framework. Each section provides:

• When to consider - Use cases and scenarios
• Key patterns - Relevant documentation files
• Decision frameworks - How to choose between options
• Trade-offs - Pros and cons of each approach

Framework Overview

R - Requirements

Focus: Understand the problem before designing

Key Questions:

• What are the performance targets? (LCP, FID, CLS)
• What's the expected scale? (users, requests/sec)
• What are the accessibility requirements? (WCAG AA/AAA)
• What browsers must be supported?
• What are the security constraints?

Relevant Content:

• Rendering strategy decisions (SSG/SSR/ISR/CSR)
• Error handling requirements
• Accessibility standards
• Performance budgets
• Security policies

A - Architecture

Focus: High-level system structure and patterns

Key Questions:

• Should we use microfrontends?
• Do we need real-time capabilities?
• What state management approach?
• How do we handle routing?
• What architectural patterns fit?

Relevant Content:

• Microfrontends architecture
• Real-time systems (WebSockets, SSE)
• State management patterns (Flux, Atoms, Signals)
• Architecture patterns (Compound, HOC, DI, Plugin)
• Event-driven architecture

D - Data Model

Focus: How data flows and is managed

Key Questions:

• How do we fetch data? (caching, deduplication)
• How do we manage state? (global, local, persistence)
• How do we sync across tabs?
• What's our caching strategy?
• How do we handle optimistic updates?

Relevant Content:

• Data fetching strategies
• State management implementations
• Caching patterns (SWR, React Query)
• Persistence strategies
• Request deduplication
• Optimistic updates

I - Interface

Focus: User experience and interface design

Key Questions:

• What design system do we use?
• How do we handle internationalization?
• What's our mobile/PWA strategy?
• How do we ensure accessibility?
• What are our form patterns?

Relevant Content:

• Design systems (tokens, theming, components)
• Internationalization (i18n, RTL, date/number formatting)
• Mobile and PWA patterns
• Accessibility patterns
• Form handling
• Keyboard navigation

O - Optimizations

Focus: Performance, scalability, and reliability

Key Questions:

• How do we optimize bundle size?
• How do we improve Core Web Vitals?
• What's our code splitting strategy?
• How do we monitor performance?
• What security measures do we implement?

Relevant Content:

• Core optimizations (assets, compression, HTTP/2)
• Visual performance (layout shift, paint, animations)
• Code splitting strategies
• Security patterns (CSP, SRI, CORS)
• Observability (tracing, profiling, monitoring)
• Testing strategies

Using RADIO in Interviews

Step-by-Step Process

1. Clarify Requirements (R) - Ask questions, understand constraints
2. Design Architecture (A) - Draw high-level diagram, explain components
3. Define Data Flow (D) - Show how data moves through the system
4. Design Interface (I) - Explain UI/UX considerations
5. Optimize (O) - Discuss performance, scalability, security

Common Patterns

Simple App (Blog, Marketing Site)

R: Static content, SEO important
A: SSG, simple routing
D: Minimal state, no persistence
I: Basic design system, single language
O: Image optimization, basic caching

Medium App (Dashboard, SaaS)

R: Dynamic content, user authentication
A: SSR/ISR, component-based
D: React Query/SWR, localStorage
I: Design system, i18n, accessibility
O: Code splitting, bundle optimization

Complex App (Social Media, E-commerce)

R: Real-time, high scale, multiple teams
A: Microfrontends, real-time architecture
D: Normalized cache, optimistic updates
I: Complex design system, multi-language
O: Advanced optimizations, observability

Navigation

Framework Sections

Explore each section of the RADIO framework:

• Requirements - Understanding the problem
• Architecture - System structure and patterns
• Data Model - Data flow and state management
• Interface - UI/UX and user interactions
• Optimizations - Performance and reliability

Practice Guides

For focused component problems (20-30 min):

• UI Components - File Upload, Lists, Editors, Modals, Tables

For complete application systems (45-60 min):

• Complete Systems - News Feed, E-commerce, Video Streaming, Travel Booking, Dashboard, Chat

Tips for Success

1. Start with R - Never skip requirements gathering
2. Think in layers - Each letter builds on the previous
3. Consider trade-offs - Every decision has pros and cons
4. Be specific - Use real patterns and technologies
5. Show depth - Demonstrate understanding of implementation details

Remember: RADIO is a guide, not a rigid structure. Adapt it to the specific problem you're solving.