A complete guide to acing frontend system design interviews — from the RADIO framework to real-world component designs asked at FAANG.
17 articles in this series
Learn the RADIO framework — Requirements, Architecture, Data Model, Interface, Optimizations — the structured method for frontend system design interviews at FAANG and top tech companies.
A complete frontend system design answer for the autocomplete / typeahead question. Covers requirements, component architecture, API design, debouncing, caching, keyboard navigation, and ARIA accessibility.
A complete frontend system design answer for designing a news feed like Facebook or Twitter. Covers architecture, infinite scroll, real-time updates, optimistic UI, virtualization, and accessibility.
A complete frontend system design answer for designing a chat application like Messenger or Slack. Covers real-time messaging with WebSockets, IndexedDB for offline support, message delivery states, optimistic UI, and cross-tab sync.
A complete frontend system design answer for designing an image carousel component. Covers architecture, CSS layout with scroll snapping, lazy loading, image preloading, touch/swipe support, autoplay, keyboard navigation, and ARIA accessibility.
A complete frontend system design answer for building a data table component. Covers the RADIO framework, column configuration, sorting, filtering, pagination, virtual scrolling, keyboard navigation, accessibility, and performance optimisation for large datasets.
A complete frontend system design answer for infinite scroll. Covers cursor-based pagination, IntersectionObserver sentinels, race conditions and duplicate requests, DOM and memory management, virtualisation, and accessibility — the way senior engineers answer it.
A complete frontend system design answer for the star rating widget. Covers half-star precision math, two-layer rendering, rating histograms, ARIA accessibility, optimistic updates, and SSR hydration — the Amazon-style interview question asked at Meta, Amazon, and Stripe.
A complete frontend system design answer for the kanban board interview question. Covers pointer-based drag-and-drop vs HTML5 DnD, fractional position ordering (Trello's real trick), optimistic moves with rollback, keyboard accessibility, offline queues, and multi-user conflict handling.
A complete frontend system design answer for the nested comments interview question. Covers normalized flat state for tree data, materialized-path storage, flattened virtualized rendering, per-thread pagination, optimistic posting with rollback, XSS-safe markdown rendering, and live sorting that doesn't fight the reader.
A complete frontend system design answer for the undo/redo interview question. Covers command pattern vs immutable snapshots, structural sharing, keystroke coalescing, bounded history with memory budgets, async race conditions, collaborative per-user undo, and browser shortcut conflicts.
A complete frontend system design answer for the spreadsheet interview question. Covers virtual scrolling for million-cell grids, sparse cell storage, formula parsing, dependency-graph recalculation with topological ordering, circular reference detection, clipboard and CSV round-trips, and optimistic collaborative editing.
A complete frontend system design answer for the date range picker interview question. Covers the selection state machine, calendar grid generation, timezone and DST date-math traps, disabled dates and minimum-stay constraints, hover previews, ARIA grid accessibility, and Booking.com-style URL sync.
A complete frontend system design answer for the email client interview question. Covers the normalized thread data model, three-pane responsive layout, virtualized thread lists, optimistic read state with delta sync, compose that survives navigation, undo send, search strategy, and offline outbox design.
A complete frontend system design answer for the collaborative editor interview question. Covers the operation-based data model, why contentEditable can't be bolted onto, OT vs CRDT with real tradeoffs, Yjs architecture, presence and cursor sync, collaborative undo, offline op-log persistence, and rendering strategy.
A complete frontend system design answer for the seat booking interview question. Covers the seat state model, optimistic selection with rollback, server-side holds with TTLs, real-time availability deltas, payment handoff races, seat map rendering and accessibility, and the oversell problem.
A complete frontend system design answer for the infinite canvas whiteboard interview question (Miro, Excalidraw, Figma-style). Covers world-space vs screen-space transforms, zoom-to-cursor math, layered canvas rendering, spatial index culling, selection handles, real-time presence cursors, undo/redo coalescing, and offline persistence.