🏗️ Feature-Based Architecture

A modern, scalable pattern for organizing large applications by domain features rather than technical concerns.

✅ Why Feature-Based Architecture?

As Next.js applications grow, traditional folder structures become difficult to maintain. Feature-based architecture offers:

• Improved maintainability: All related code lives together
• Better scalability: Features can be developed and tested independently
• Easier onboarding: Clear boundaries help new developers understand the codebase
• Reduced cognitive load: Developers focus on one feature at a time
• Simplified refactoring: Entire features can be removed or updated with minimal impact

🧠 Core Concepts

In the App Router, we organize around domain features rather than technical layers. Each feature folder contains all related code:

• UI components
• API handlers and services
• Custom hooks
• Type definitions
• Utilities and constants
• Tests

This colocation approach follows the principle of "grouping what changes together."

📦 Folder Structure

/src
  /app
    /(features)              # Feature modules
      /admin                 # Admin feature module
        /components          # Admin-specific components
        /hooks               # Admin-specific hooks
        /services            # Admin-specific services
        /types               # Admin-specific types
        /posts               # Nested feature: posts management
          /components
          /hooks
          /services
          /test
          page.tsx
        /ads                 # Nested feature: ads management
          /components
          /hooks
          /services
          /test
          page.tsx
        layout.tsx           # Admin layout
        page.tsx             # Admin dashboard
      /posts                 # Posts feature module
        /components
          PostCard.tsx
          PostList.tsx
        /hooks
          usePosts.ts
          usePostActions.ts
        /services
          posts.api.ts
          posts.service.ts
        /types
          index.ts
        page.tsx
        loading.tsx
        error.tsx
      /users                 # Users feature module
        /components
          UserProfile.tsx
          UserList.tsx
        /hooks
          useUsers.ts
        /services
          users.service.ts
        page.tsx
    /api                     # API routes
      /posts
        route.ts
      /users
        route.ts
  /components                # Shared components
    /ui                      # Primitive components
    /layout                  # Layout components
  /lib                       # Shared utilities
  /types                     # Global type definitions
  /styles                    # Global styles

🛠️ Implementation Guidelines

Feature Module Structure

Each feature should be self-contained with its own types, services, hooks, and components.

Shared Dependencies

For code shared across features, use the shared folders in /components, /lib, and /types.

🧪 Testing Strategy

Implement a testing strategy that aligns with the feature structure, with tests colocated within each feature or in dedicated test folders.

📝 Best Practices

1. Strict boundaries: Avoid importing between features; use shared libraries instead
2. Consistent naming: Use clear, consistent naming conventions across features
3. Document dependencies: Clearly document external dependencies for each feature
4. API colocation: Keep API calls close to where data is used
5. Progressive adoption: Migrate gradually rather than all at once

🔄 Migration Tips

1. Start with new features: Implement new functionality using the feature-based approach
2. Refactor incrementally: Gradually migrate existing code when making changes
3. Identify boundaries: Look for natural feature boundaries in your existing code
4. Create shared libraries: Extract common utilities and components as you refactor
5. Use path aliases: Simplify imports with TypeScript path aliases

🚀 Final Thoughts

Feature-based architecture in Next.js provides a scalable, maintainable structure for growing applications. By organizing code around business domains rather than technical concerns, teams can work more efficiently and create a more sustainable codebase.

This approach aligns perfectly with modern development practices and prepares your application for future growth and evolution.