Start with a familiar UI problem
Practice global ownership, visible limits, timer cleanup, and accessible announcements in a junior-sized prompt.
Design a toast notification systemRecommended preparation
Architecture interview prep
Frontend System Design Interview: Questions & Practice
Use each card's timebox for a focused first pass, then expand the same decisions with the separate 45-minute RADIO interview template.
23frontend prompts
4question formats
7free full solutions
16premium breakdowns
Common questions
Common frontend system design interview questions
These core frontend system design patterns cover application architecture, UI component systems, realtime interfaces, AI product workflows, and senior/staff tradeoff rounds.
Infinite listsInfinite Scroll System Design: Frontend Interview AnswerPagination, virtualization, loading states, and scroll performance.Notification systemsDesign a Toast Notification SystemGlobal toast APIs, timers, stacking, portals, cleanup, and accessible announcements.Autocomplete and searchReal-time Search with Debounce & CachingDebounce, cancellation, stale responses, caching, and perceived speed.Feeds and timelinesNews Feed / Timeline Front-End System DesignFeed hydration, cursor pagination, media lazy loading, and realtime updates.Streaming chatDesign an AI Chat Composer and Streaming TurnIME composition, attachments, submit/cancel/retry, and current-turn streaming.Design systemsComponent-driven Design System ArchitectureTokens, component APIs, accessibility contracts, theming, and versioning.Realtime collaborationLive Comments for Global Streams (Real-time)WebSocket/SSE updates, buffering, moderation UI, and burst control.Staff-level dashboardsDrag-and-Drop Dashboard Frontend System DesignLayout persistence, drag/resize performance, constraints, and ownership boundaries.
Start here
Build from a junior UI boundary to a senior architecture case
Follow this four-step path when you are new to the bank, then use the filters to choose focused practice.
Learn the RADIO answer sequence
Use Requirements, Architecture, Data, Interface, and Optimizations to make your decisions easy to follow.
Open the RADIO frameworkHandle async sends and streaming
Move to IME-safe sending, attachment readiness, stop/retry behavior, and stale stream protection.
Design an AI chat composerFinish with a senior layout case
Defend drag, resize, persistence, migration, performance, and ownership decisions across responsive layouts.
Design a customizable dashboardQuestion bank
Frontend system design prompt bank
23 prompts shown
Junior10 min first passFree
UI component systems
Design a Toast Notification System
A dismiss timer racing a user action must remove one toast once while overflow waits and announcements do not repeat.
- State ownership
- Lifecycle cleanup
- Race handling
Mid15 min first passFree
UI component systems
Design a Resilient Checkout and Payment Flow
A lost payment response and competing browser tabs must converge without duplicate charges, stale totals, exposed card data, or false completion.
- Authority modeling
- Idempotent recovery
- Secure payment UX
Mid15 min first passFree
Application architecture
Infinite Scroll System Design: Frontend Interview Answer
Page retries and changing results must extend a long list without duplicates, scroll jumps, unbounded DOM growth, or an inaccessible loading trap.
- Infinite Scroll
- Intersection Observer
- Pagination
Mid15 min first passPremium
UI component systems
Multi-step Form with Autosave
A late autosave must never overwrite newer edits while users change steps, restore drafts, resolve conflicts, and recover submission.
- Forms
- Autosave
- Validation
Mid15 min first passPremium
Realtime and data-heavy UI
Real-time Search with Debounce & Caching
A slower old query must never replace newer results while cancellation, caching, empty states, and keyboard navigation remain predictable.
- Search
- Debounce
- Caching
Mid15 min first passPremium
UI component systems
Image Upload & Preview Component
Cancel, retry, and finalize may arrive out of order; previews, progress, object URLs, and errors must still converge safely.
- Images
- Upload
- Validation
Mid15 min first passPremium
Application architecture
Flashcard-based Language Learning App
Offline study sessions must merge progress without losing answers while reveal controls, feedback, motion preferences, and synchronization stay accessible.
- Flashcards
- Language Learning
- Accessibility
Mid15 min first passFree
AI product workflows
Design an AI Chat Composer and Streaming Turn
An old Send, Stop, or stream event must never change the active reply while IME input, attachments, and drafts remain intact.
- IME-safe input
- Command idempotency
- Stream reconciliation
Mid15 min first passPremium
AI product workflows
AI Image Generation MVP (Two-Week Design)
An accepted image job may stall, retry, or finish after Cancel; the UI must show honest progress and recover safe media.
- Ux
- Api Calls
- Real Time
Mid15 min first passPremium
AI product workflows
Design an AI-Assisted Bulk Edit Review Flow
AI-proposed record changes require versioned approval, then must expose partial success, Cancel races, and verified rollback honestly.
- Authority boundaries
- State modeling
- Mixed-outcome recovery
Mid15 min first passPremium
UI component systems
UI Component and State Design From a Mock
A support-inbox mock must become clear component, URL, server, and draft boundaries without focus loss or contradictory optimistic state.
- Components
- State Management
- Architecture
Senior20 min first passFree
Application architecture
Gmail-Style Offline Email Client Frontend System Design
Connectivity recovery must preserve newer local drafts, avoid duplicate sends, and explain whether each action is queued or confirmed.
- Offline First
- State Management
Senior20 min first passFree
AI product workflows
AI Agent Run Inspector Frontend System Design
Late spans, tool calls, and approvals must reconstruct one trustworthy run without exposing redacted data or losing keyboard navigation.
- Real Time
- Streams
- State Management
Senior20 min first passPremium
Realtime and data-heavy UI
Endless Short-Video Feed (TikTok-Style)
Rapid swipes and weak networks must keep one video responsive without runaway preloading, media-memory growth, or a broken recovery path.
- Infinite Scroll
- Virtualization
- Performance
Senior20 min first passPremium
Realtime and data-heavy UI
Scalable Notifications Feed (Real-time)
Reconnects and traffic bursts must preserve notification order and unread meaning without duplicate items, unbounded storage, or a frozen feed.
- Notifications
- Real Time
- Performance
Senior20 min first passPremium
Realtime and data-heavy UI
Live Comments for Global Streams (Real-time)
Bursty comments and late moderation events must converge without unreadable auto-scroll, reordered messages, or inaccessible controls.
- Real Time
- Streams
- Performance
Senior20 min first passPremium
Application architecture
Netflix Continue Watching Frontend System Design
Progress from multiple devices must reconcile into a stable Continue Watching row without focus loss, stale percentages, or wasteful media loading.
- Frontend Architecture
- Architecture
- Performance
Senior20 min first passFree
UI component systems
Drag-and-Drop Dashboard Frontend System Design
Drag and resize must stay responsive while layouts persist safely across conflicts, migrations, keyboard input, and responsive breakpoints.
- Dashboard
- Drag Drop
- Performance
Senior20 min first passPremium
Realtime and data-heavy UI
Live Chart Rendering (High Frequency Updates)
Bursty samples can arrive faster than paint; the chart must bound memory, recover gaps, and remain readable without inventing data.
- Charts
- Real Time
- Performance
Senior20 min first passPremium
UI component systems
Component-driven Design System Architecture
A component release must evolve tokens and APIs without silently breaking accessibility, themes, consumers, or the migration path.
- Design System
- Theming
- Performance
Senior20 min first passPremium
Application architecture
Cross-device Preferences Sync
Two devices may edit the same preference from stale revisions without creating conflicts for unrelated settings.
- State Management
- Local Storage
- Caching
Senior20 min first passPremium
AI product workflows
Real-time Model Training Dashboard
Metric streams can reconnect with gaps or stale runs; comparisons must resume without implying missing samples are current.
- Real Time
- Streams
- Performance
Senior20 min first passPremium
Realtime and data-heavy UI
News Feed / Timeline Front-End System Design
Ranked pages and live updates must merge without duplicate stories, scroll jumps, unbounded rendering work, or client-invented order.
- Infinite Scroll
- Virtualization
- Performance
Choose your focus
Connect system design to the rest of frontend interview prep
Use these related practice areas when a design prompt exposes a coding, JavaScript, guided-plan, or company-prep gap.
What gets tested
Frontend system design is not backend diagramming
Strong answers explain how UI behavior, network data, component contracts, and performance constraints fit together under product pressure.
Requirements
Clarify users, success metrics, latency, device constraints, and edge cases before drawing UI boxes.
Architecture
Split client state, server data, rendering paths, routing, and ownership boundaries into defendable pieces.
Data model
Define the entities, cache keys, pagination windows, optimistic updates, and stale-data behavior.
Interface
Explain component contracts, accessibility states, loading/error UX, and interaction affordances.
Optimizations
Choose tradeoffs for performance, virtualization, streaming, resilience, monitoring, and graceful degradation.
Question formats
Practice common frontend system design formats
The bank separates product-scale app architecture, component systems, realtime UI, and AI product workflows so practice does not become random prompt browsing.
Dashboards, feeds, preferences, multi-step flows, and feature slices where ownership and data flow matter.
Design systems, forms, uploaders, toasts, drag/drop, accessibility states, and reusable contracts.
Notifications, live comments, charts, streams, infinite scroll, caching, and high-frequency updates.
Streaming chat, image generation, model-progress dashboards, resilience, cancellation, and user control.
How to answer
Use RADIO to turn each prompt into a structured answer
Read the framework once, then use the prompt bank above to drill one part of the answer at a time.
Frontend system design interview rubric
What a strong frontend design answer should cover
Strong answers are judged on architecture quality, user-visible failure handling, and how clearly you explain tradeoffs under changing constraints.
Requirements
Defines users, scope, non-goals, scale, latency, and success metrics.
Architecture
Shows rendering strategy, state boundaries, route ownership, and service contracts.
Data/state
Separates server data, client state, cache, optimistic queues, and transient UI state.
APIs/events
Explains payloads, pagination, mutations, realtime events, retries, and cancellation.
Interface/accessibility
Covers component APIs, loading/error/empty states, keyboard behavior, and announcements.
Performance/reliability
Sets budgets, chooses optimizations, handles failure modes, and adds observability.
Communication
Narrates tradeoffs clearly and adapts when requirements change.
Common mistakes
Avoid common gaps in frontend system design answers
The most common failures are not missing a library name; they are unclear scope, weak state ownership, and untested tradeoffs.
Jumping into components too early
Clarify scope, users, scale, and success metrics before drawing the component tree.
Giving vague state management answers
Separate local UI state, shared client state, server state, cache state, and hot interaction state.
Ignoring rendering and caching strategy
Name SSR/CSR tradeoffs, cache keys, freshness rules, invalidation, and perceived performance.
Skipping accessibility, security, and reliability
Include keyboard flows, ARIA states, safe rendering, auth boundaries, retry, and fallback behavior.
Not naming tradeoffs
Explain why the chosen architecture beats at least one alternative under the given constraints.
Premium preview
Locked prompts still show the interview shape before upgrade
Free users can inspect the prompt, tags, format, and guide path. Premium unlocks the full RADIO breakdown and tradeoff framing for senior-level answers.
- Full RADIO breakdowns for premium prompts
- Tradeoff framing for state, APIs, caching, rendering, and performance
- Locked prompt previews explain the case while full premium solutions stay protected
FAQ
Frontend system design interview questions FAQ
What is a frontend system design interview?
A frontend system design interview is an architecture round focused on client-side decisions: rendering strategy, state ownership, API contracts, caching, accessibility, performance, resilience, and product tradeoffs.
Which frontend system design interview question should I practice first?
Start with a familiar UI boundary such as a toast notification system, then move to autocomplete, infinite scroll, realtime interfaces, and senior-level dashboards as the tradeoffs become harder.
What frontend system design questions are commonly asked?
Common prompts include infinite scroll, autocomplete search, notification systems, news feeds, chat interfaces, dashboards, design systems, file upload components, and realtime collaboration surfaces.
How is frontend system design different from backend system design?
Frontend system design still needs backend awareness, but the scoring centers on UI architecture, rendering, browser performance, accessibility, client/server state boundaries, and failure states users can see.
Should I start with app architecture or UI components?
Start with app architecture when the prompt is product-scale, such as feeds or dashboards. Start with UI component architecture when the prompt is an interaction-heavy component, such as autocomplete, modal, upload, or design system primitives.