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SoFi·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Apr 2026

Summary

SoFi software engineer round that was basically one big frontend system design question. More depth than I expected for what I thought would be a standard coding screen.

Questions Asked (1)

Q1

Build a React data table with full CRUD support, pagination, sorting, inline editing, form validation, optimistic updates, and error handling. Walk through your state management approach, component structure, accessibility, and performance considerations like virtualization and memoization.

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

This was a lot.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a component architecture with a clear separation of concerns. Discuss state management (server state vs UI state), data fetching, and how you'd handle CRUD operations with optimistic updates and error handling. Finally, cover accessibility and performance optimizations like virtualization and memoization, explaining trade-offs.

Pro tip: Emphasize that you'd use a library like React Query or SWR for server state to handle caching, optimistic updates, and error retries, while keeping UI state local. This shows you understand the distinction and avoid reinventing the wheel.

1. Clarify Requirements and Constraints

Ask about data volume, real-time updates, API design, and browser support to tailor your solution. This demonstrates you consider context before diving into implementation.

2. Design Component Structure and State Management

Propose a component hierarchy (e.g., DataTable, TableHeader, TableRow, EditableCell) and decide on state management: local state for UI, server state with a library like React Query for data fetching and mutations.

3. Implement CRUD with Optimistic Updates and Error Handling

Explain how you'd handle create, read, update, delete operations, using optimistic updates for responsiveness and rolling back on error. Discuss error boundaries, toasts, and retry logic.

4. Address Accessibility and Performance

Cover ARIA roles, keyboard navigation, and focus management. For performance, discuss virtualization (react-window, react-virtualized) and memoization (React.memo, useMemo, useCallback) to avoid unnecessary re-renders.

5. Discuss Trade-offs and Testing

Summarize trade-offs (e.g., library vs custom, virtualization complexity) and mention testing strategies (unit, integration, E2E) to ensure reliability.

Key Points to Mention

  • Separation of server state and UI state; using React Query or SWR for caching, optimistic updates, and error handling.
  • Component composition and controlled vs uncontrolled components for inline editing.
  • Form validation strategies: client-side with libraries like Formik + Yup, and server-side validation.
  • Accessibility: ARIA roles (grid, row, columnheader), keyboard navigation (arrow keys, Enter to edit), and focus management.
  • Performance: virtualization for large datasets, memoization to prevent re-renders, and debouncing for search/filter.
  • Error handling: optimistic update rollback, error boundaries, user notifications, and retry mechanisms.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.