1. How do you structure Redux Toolkit in a large-scale React app (folder structure)?

Organizing Redux Toolkit Structure in Large-Scale React Applications

In large-scale React applications, a well-structured Redux Toolkit setup improves scalability, maintainability, and team collaboration. The goal is to separate concerns by feature or domain rather than by type (e.g., actions, reducers).

Recommended Folder Structure (Feature-Based)

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src/
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├── app/
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│ ├── store.js → Configures the Redux store using configureStore
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│ └── rootReducer.js → Combines feature slices (optional if small)
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├── features/
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│ ├── users/
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│ │ ├── usersSlice.js → Contains createSlice and reducers
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│ │ ├── usersApi.js → Defines RTK Query endpoints (optional)
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│ │ └── UsersList.jsx → Feature-specific UI components
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│ ├── posts/
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│ │ ├── postsSlice.js
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│ │ ├── postsApi.js
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│ │ └── PostItem.jsx
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├── components/ → Shared reusable UI components
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├── hooks/ → Custom React hooks (e.g., useAuth, useTheme)
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├── services/ → Common API logic or helper functions
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├── utils/ → Utility functions or constants
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└── index.js / main.jsx → App entry point

Example: store.js

This modular structure allows each feature to encapsulate its state, API calls, and UI components, making it easier to scale the application as new features are added.

Difficulty: 7/10

Topics: folder organization, feature slicing, store composition

Scenario Questions

0-2 years experience

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If you need to add a new feature that has its own slice, where would you place the slice file and why?
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How would you import the reducer from that slice into the store given a typical folder layout?
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What happens if you put all slices in a single file in a large app?

2-5 years experience

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You notice two feature slices are tightly coupled and need to share logic; how would you reorganize the folder structure to avoid circular imports?
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During a code review the store file is growing large; what refactoring would you propose to keep the store maintainable?
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A new team wants to add a slice but the project uses a 'features' folder per domain; how would you guide them to integrate it without breaking existing imports?

5-8 years experience

1
Explain how you would structure the Redux Toolkit store to support code‑splitting and lazy‑loaded reducers in a micro‑frontend environment.
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What folder conventions would you adopt to ensure type safety and easy testing when the app scales to hundreds of slices?
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How would you handle versioning of slice APIs across multiple teams while keeping the folder layout consistent?

8+ years experience

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Design a long‑term folder strategy for Redux Toolkit that accommodates both legacy code and an upcoming migration to RTK Query, considering cross‑team ownership.
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How would you evaluate trade‑offs between a feature‑first folder hierarchy versus a domain‑driven one for a multi‑product monorepo?
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If you need to introduce a shared utilities layer for slices without creating circular dependencies, what architectural changes would you propose?

Follow-up Questions

❓Can you walk me through how you’d add a new slice today?
❓What would you change if the app grew to 200 slices?
❓How do you ensure new contributors understand the folder conventions?