Claude Code Project Structure Best Practices

Introduction

Your project structure is a form of communication. Every folder name, every file location, every directory hierarchy sends signals about what code does and where functionality lives. When you work with Claude Code, this communication becomes critical because Claude reads file paths to understand context before generating code.

A well-organized project gives Claude the information it needs to make intelligent decisions. When Claude sees src/services/auth.js, it immediately understands this is a service module handling authentication. When it sees components/UserProfile/UserProfile.tsx, it knows this is a UI component following a component-per-folder pattern. These signals reduce ambiguity and produce better code.

A poorly organized project does the opposite. When files are scattered randomly, when naming is inconsistent, when similar functionality lives in different places, Claude has to guess. And guesses lead to code that might work but does not fit your architecture.

This guide covers the project structures that help Claude understand your codebase and generate code that feels like it was written by someone who has worked on your project for years.

Why Structure Matters for AI

Claude Code does not have institutional knowledge about your project. Every session starts fresh. The only context Claude has comes from reading your files, and the first thing it reads is often the file path itself.

File Paths as Context

When you ask Claude to modify a file, it parses the path for meaning. Consider these two paths:

• utils/helpers.js - Generic utilities, probably stateless functions
• services/api/userService.js - API service for user operations, likely with async methods

The second path tells Claude significantly more about what the file should contain, what patterns to use, and how the code should be structured. This context propagates into every line of generated code.

Good Structure Equals Better Suggestions

When your project follows clear conventions, Claude can extrapolate patterns. If it sees that all your React components live in src/components/ with co-located CSS modules, it will generate new components following the same pattern without being asked. If your services all return { success, data, error } objects, Claude will match that contract.

Conversely, if your project mixes patterns, say some components in components/, others in pages/, still others in features/, Claude cannot establish a baseline. It will generate code that works but may not match your team's preferences.

Poor Structure Confuses AI

The worst outcome is a structure that actively misleads. If you have a utils/ folder that contains business logic, or a components/ folder with API calls, Claude will inherit these antipatterns. AI amplifies what it sees in your codebase, good patterns and bad patterns alike.

Recommended Root Files

Certain files in your project root serve as primary documentation for both humans and AI. These files should exist in every project that uses Claude Code.

CLAUDE.md - Project Instructions

CLAUDE.md is your direct communication channel with Claude. This file is automatically read at the start of every session, making it the perfect place for project-specific instructions, conventions, and constraints.

• Project description and purpose
• Tech stack and framework versions
• Coding conventions and style rules
• Files or patterns to avoid modifying
• Testing requirements and commands

ECOSYSTEM.md - Data Models and Contracts

ECOSYSTEM.md defines your data layer: field names, types, enums, and API contracts. This is especially critical for multi-platform projects where iOS, Web, and backend must share identical schemas. Claude references this file to ensure field names match exactly across all code it generates.

COORDINATION.md - Active Work Tracking

COORDINATION.md tracks work in progress across sessions. When you close a conversation mid-task, this file tells the next session where you left off. It is your project's short-term memory, ensuring continuity even when context resets.

README.md - Project Overview

The standard README.md provides orientation for anyone new to the project, including Claude. Include setup instructions, architecture decisions, and links to deeper documentation. Claude uses this to understand the big picture before diving into specific files.

Folder Organization

A clean folder structure separates concerns and makes navigation intuitive. While specific structures vary by project type, certain patterns work universally well.

src/ - Source Code

All application source code lives here. This separation keeps build artifacts, configuration, and documentation from cluttering your main code directories. Inside src/, organize by feature or layer depending on project size.

tests/ - Test Files

Dedicated test directory or co-located tests, pick one pattern and stick to it. If tests live in tests/, mirror your src/ structure. If tests are co-located, use consistent naming like component.test.js or __tests__/ folders.

docs/ - Documentation

Longer-form documentation, architecture decisions, API docs, and guides live here. Keep README.md in the root as the entry point, with docs/ containing everything that would make the README unwieldy.

scripts/ - Automation

Build scripts, deployment automation, development utilities, and validation tools belong in scripts/. This keeps operational code separate from application code while making automation discoverable.

project-root/
  CLAUDE.md           # AI instructions
  ECOSYSTEM.md        # Data models
  COORDINATION.md     # Active work
  README.md           # Overview
  package.json        # Dependencies
  src/
    components/       # UI components
    services/         # Business logic
    utils/            # Utilities
    types/            # Type definitions
  tests/
    unit/             # Unit tests
    integration/      # Integration tests
  docs/
    architecture.md   # Design docs
    api.md            # API reference
  scripts/
    build.sh          # Build automation
    deploy.sh         # Deployment

Platform-Specific Patterns

Different project types benefit from different organizational approaches. Here are patterns that work well with Claude Code for common project types.

Web Projects (React, Vue, etc.)

Modern frontend frameworks benefit from feature-based organization at scale, but component-based organization works well for smaller projects.

src/
  components/
    Button/
      Button.tsx
      Button.module.css
      Button.test.tsx
      index.ts
    Modal/
      Modal.tsx
      Modal.module.css
  hooks/
    useAuth.ts
    useLocalStorage.ts
  services/
    api.ts
    auth.ts
  pages/
    Home.tsx
    Dashboard.tsx
  types/
    user.ts
    api.ts

Mobile Projects (iOS, Android)

Mobile projects typically organize by layer with clear separation between UI, business logic, and data access.

Sources/
  App/
    AppDelegate.swift
    SceneDelegate.swift
  Views/
    Home/
      HomeView.swift
      HomeViewModel.swift
    Profile/
      ProfileView.swift
      ProfileViewModel.swift
  Services/
    AuthService.swift
    APIService.swift
  Models/
    User.swift
    Task.swift
  Utilities/
    Extensions.swift
    Constants.swift

Backend Projects (Node, Python)

Backend services benefit from clear separation between routes, controllers, services, and data access layers.

src/
  routes/
    users.js
    tasks.js
  controllers/
    userController.js
    taskController.js
  services/
    userService.js
    taskService.js
  models/
    User.js
    Task.js
  middleware/
    auth.js
    validation.js
  config/
    database.js
    environment.js

Full-Stack Monorepos

Monorepos require clear package boundaries. Use workspaces or a tool like Turborepo to manage multiple packages.

packages/
  web/
    src/
    package.json
  mobile/
    Sources/
    Package.swift
  api/
    src/
    package.json
  shared/
    types/
    utils/
    package.json
CLAUDE.md
ECOSYSTEM.md
package.json       # Workspace root

What to Include in CLAUDE.md

Your CLAUDE.md file shapes how Claude approaches every task in your project. A well-written CLAUDE.md can dramatically improve code quality.

Project Description

Start with a brief description of what the project does and who uses it. This context helps Claude make appropriate decisions about complexity, error handling, and user experience.

Tech Stack

List your frameworks, libraries, and versions. Include build tools and testing frameworks. This prevents Claude from suggesting incompatible solutions or deprecated APIs.

# Tech Stack
- React 18 with TypeScript
- Vite for building
- Tailwind CSS for styling
- React Query for data fetching
- Vitest for testing

Folder Explanations

Document what each major directory contains and when to use it. This prevents Claude from putting code in the wrong place.

# Directory Structure
- src/components/ - Reusable UI components
- src/features/ - Feature-specific code (components, hooks, utils)
- src/services/ - API calls and external integrations
- src/hooks/ - Shared custom hooks
- src/utils/ - Pure utility functions (no side effects)

Coding Conventions

Document patterns your team follows. Be specific about naming, file organization, and preferred approaches.

# Conventions
- Use named exports, not default exports
- Components use PascalCase (UserProfile.tsx)
- Hooks use camelCase with 'use' prefix (useAuth.ts)
- Always handle loading and error states
- Write tests for all services and complex hooks

What NOT to Do

Certain organizational patterns actively harm Claude's ability to help you. Avoid these common mistakes.

Giant Files with Mixed Concerns

Files over 500 lines become hard for Claude to reason about. Worse, files that mix UI, business logic, and data access provide conflicting signals about where new code should go. Split large files by responsibility.

Deeply Nested Structures

Paths like src/features/user/components/profile/cards/avatar/AvatarCard.tsx are hard to navigate and provide little additional context beyond src/components/AvatarCard.tsx. Keep nesting to 3-4 levels maximum.

Inconsistent Naming

If some files use camelCase, others use kebab-case, and still others use PascalCase, Claude cannot establish a pattern. Pick one convention per file type and enforce it everywhere.

Missing README or Documentation

Without documentation, Claude must infer project purpose from code alone. This leads to technically correct but contextually wrong solutions. A brief README prevents many misunderstandings.

Example Structures

Here are complete examples you can use as starting points for your own projects.

Simple Web Application

A straightforward React application with authentication, API calls, and basic state management.

my-app/
  CLAUDE.md
  README.md
  package.json
  src/
    components/
      Button.tsx
      Modal.tsx
      Navbar.tsx
    pages/
      Home.tsx
      Login.tsx
      Dashboard.tsx
    services/
      api.ts
      auth.ts
    hooks/
      useAuth.ts
      useApi.ts
    types/
      index.ts
    App.tsx
    main.tsx
  tests/
    components/
    services/
  public/
    index.html

Multi-Platform Project

A project with iOS, Web, and Firebase backend sharing data models and conventions.

my-platform/
  CLAUDE.md             # AI instructions for all platforms
  ECOSYSTEM.md          # Shared data models
  COORDINATION.md       # Cross-platform work tracking
  README.md

  web/
    src/
      components/
      services/
      types/            # Generated from ECOSYSTEM.md
    package.json

  ios/
    Sources/
      Views/
      Services/
      Models/           # Matches ECOSYSTEM.md exactly
    Package.swift

  firebase/
    functions/
      src/
        index.ts
        users.ts
        tasks.ts
    firestore.rules
    package.json

  scripts/
    validate-schemas.sh # Ensures all platforms match

Conclusion

Project structure is not just about organization; it is about communication. Every folder you create, every naming convention you follow, every file you place sends signals to both human developers and AI assistants about how your codebase works.

The time you invest in structure pays dividends in every interaction with Claude Code. Clear organization leads to better code suggestions, fewer corrections, and faster development. Poor organization leads to constant steering and cleanup.

Start with the fundamentals: create CLAUDE.md, ECOSYSTEM.md, and a clean README.md. Organize your source code with clear separations between components, services, and utilities. Pick naming conventions and follow them relentlessly.

Then let Claude do what it does best: generate code that fits seamlessly into the architecture you have established. When your structure speaks clearly, Claude listens and responds with code that feels like it belongs.