🚀 Scaling React Like Big Tech: Folder Structures, Clean Code & Beyond

[Mursal Furqan Kumbhar]

Hey Everyone ​

I know it's been quite a long gap since my last article. But we are finally back with a bang.

So if you’ve ever wondered how Airbnb, Shopify, or Meta keep their codebases sane while thousands of engineers ship features daily — the answer is simple: structure + discipline + automation.

This isn’t about writing code that just works. It’s about writing code that:

• Scales with your team.
• Survives onboarding of 10 new devs.
• Passes reviews without a hundred nitpicks.
• And doesn’t make you cry when you open it six months later.

Let’s break down what the big companies do differently — and how you can bring those practices into your own projects.

Folder Structure that Scales​

Top companies don’t just throw files into a random components/ folder and hope for the best. They use feature-driven architecture, which grows naturally with the product.

Traditional (Bad) Structure​

src/
├── components/
│   ├── Button.jsx
│   ├── Card.jsx
│   ├── Form.jsx
├── services/
├── hooks/
└── App.jsx

This looks fine at first… until your app has 300+ components and no one knows which belongs to what.

Scalable (Feature-Based) Structure​

src/
├── features/
│   └── auth/
│       ├── components/
│       ├── hooks/
│       └── services/
├── shared/
│   ├── ui/
│   └── utils/
└── App.jsx

Key Difference: Everything related to a single feature (Auth, Products, Cart, etc.) is grouped. Shared logic/components live in shared/.

Approach	Pros	Cons
Traditional (by type)	Simple to start	Becomes chaos at scale
Feature-Based	Easy ownership, scalable, testable	Slightly more setup upfront

Design Systems & UI Libraries​

Big companies don’t reinvent the button every Tuesday. They use design systems and UI libraries.

• Airbnb → Lona
• Shopify → Polaris
• Meta → Reusable UI + strict guidelines

Tools you can use: Chakra UI, Tailwind + Headless UI, Radix UI

Visual Example​

Without Design System:

<Button variant="danger" color="red" bg="red" />

With Design System:

<DeleteButton />

Why Use Design Systems?	Benefits
Consistency	UI looks the same across app
Speed	Devs move faster
Accessibility	Built-in ally support
Brand Identity	Product feels cohesive

Hooks = Where Logic Lives​

Business logic doesn’t belong inside components. Custom hooks make code reusable, testable, and clean.

Example:​

// useProduct.js
export function useProducts() {
   const [data, setData] = useState([])
   useEffect(() => {
      fetchProducts().then(setData)
   }, [])
   return data
}

UI stays declarative.
Logic stays modular.

Diagram: Components vs Hooks

[Component] ---> UI (render)
       |
       v
 [Custom Hook] ---> Data Fetching, State, Business Logic

Clean Code = Scalable Code​

Big tech engineers follow clean code principles:

• SRP → Single Responsibility Principle
• KISS → Keep It Simple, Stupid
• DRY → Don’t Repeat Yourself

Bad	Good
<Button variant="danger" color="red" bg="red" />	<DeleteButton />

Abstraction = Fewer Bugs + Cleaner Reviews

Real-Time Code Reviews + Linting​

At big companies, automation + reviews are mandatory.

• Code Reviews → shared knowledge
• Pre-Commit Hooks (Husky) → catch errors early
• ESLint + Prettier → consistent style

CI/CD Pipeline Visual​

[Developer Pushes Code] 
       |
       v
[Pre-Commit Checks: Lint + Tests]
       |
       v
[Pull Request Review]
       |
       v
[CI/CD: Build + Deploy + Monitor]

Security & Accessibility First​

Security isn’t optional. Accessibility isn’t either.

Security Checklist​

• Prevent XSS and CSRF
• Proper token handling
• Input validation

Accessibility Checklist​

• Keyboard navigation works
• Screen reader support
• High color contrast

Use tools like axe-core, eslint-plugin-jsx-ally, lighthouse.

Automation + Monitoring​

Big teams don’t just ship code — they ship pipelines + monitoring.

• CI/CD Pipelines (GitHub Actions, Vercel, CircleCI)
• Bundle Size Alerts
• Error Tracking (Sentry, Datadog)
• Performance Monitoring (Lighthouse CI)

Example:

Commit → Build → Test → Deploy → Monitor

Documentation & Knowledge Sharing​

What separates side projects from real companies?
Documentation.

• Good README.md = contributor-friendly.
• Internal wikis = no lost knowledge.
• ADRs (Architecture Decision Records) = explain why choices were made.

Culture = The Invisible Architecture​

Finally — even the best code structure won’t save a bad culture. Big companies win because:

• PRs = conversations, not fights.
• Automation is embraced, not skipped.
• Docs + testing = part of “done”.

At the end of the day, how your team codes together matters more than folder names.

Startup vs Big Tech Codebases​

Here’s how things usually look in a scrappy startup vs how big tech organizes for scale:

┌────────────────────┐           ┌─────────────────────────┐
│   Startup Style    │           │     Big Tech Style      │
├────────────────────┤           ├─────────────────────────┤
│ 📂 components/     │           │ 📂 features/auth/       │
│ 📂 hooks/          │           │   ├── components/       │
│ 📂 services/       │           │   ├── hooks/            │
│ App.jsx            │           │   └── services/         │
│                    │           │ 📂 shared/ui/           │
│ Easy to start ✅   │           │ 📂 shared/utils/        │
│ Chaos later ❌      │           │ Scales across teams ✅  │
└────────────────────┘           └─────────────────────────┘

Side-by-Side Table​

Aspect	Startup-Style	Big Tech-Style
Folder Structure	Flat, all components in one folder	Feature-based, modular
UI	Custom each time	Design system + UI library
Logic	Inside components	Extracted into hooks
Code Quality	Quick fixes, less abstraction	Clean code, reusable patterns
Reviews	Ad-hoc, sometimes skipped	Mandatory PRs + linting + tests
Security	Later concern	Built-in from day one
Docs	README only	Wikis + ADRs + onboarding guides
Culture	“Move fast, break things”	“Move fast, don’t break prod”

Final Takeaway​

Big companies scale not because their engineers are magical unicorns , but because they follow battle-tested practices:

• Organize code by features, not file types.
• Use design systems for UI.
• Extract logic into hooks.
• Follow clean code principles.
• Automate reviews + pipelines.
• Prioritize security & accessibility.
• Write documentation.
• Build a team culture around consistency.
• Startups often optimize for speed, but end up with technical debt.
• Big Tech optimizes for scalability, making onboarding, reviews, and growth smooth.
• The sweet spot? Start with startup speed, but gradually adopt Big Tech practices before chaos hits.

Happy Hacking ​

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