Express Documentation Generator

An npx CLI tool that automatically generates comprehensive API documentation for Express.js applications by analyzing your code.

Features

• 🔍 Automatic Route Discovery - Finds all Express routes by parsing your application code
• 📊 Response Analysis - Extracts status codes and response structures from route handlers
• 🔧 Middleware Detection - Identifies both global and route-specific middleware
• 📄 Multiple Output Formats - Generates both JSON and Markdown documentation
• 💬 Comment Extraction - Includes JSDoc comments as route descriptions
• 🚀 Zero Configuration - Works out of the box with any Express.js application

Installation

# Run directly with npx (recommended)
npx create-express-doc <your-app.js>

# Or install globally
npm install -g create-express-doc
create-express-doc <your-app.js>

Usage

Basic Usage

npx create-express-doc app.js

Advanced Options

# Specify output directory
npx create-express-doc app.js --output-dir ./documentation

# Custom JSON filename
npx create-express-doc app.js --json-name my-api-docs.json

# Custom README filename
npx create-express-doc app.js --readme-name API-DOCS.md

# Exclude middleware information
npx create-express-doc app.js --no-middleware

# Include source file references
npx create-express-doc app.js --include-source

# Skip documentation validation
npx create-express-doc app.js --no-validate

# Skip summary report
npx create-express-doc app.js --no-summary

CLI Options

Option	Description	Default
--output-dir <dir>	Output directory for documentation	./docs
--json-name <name>	JSON file name	api-documentation.json
--readme-name <name>	README file name	README.md
--no-middleware	Exclude middleware information	false
--include-source	Include source file references	false
--no-validate	Skip documentation validation	false
--no-summary	Skip summary report	false
-h, --help	Show help message	-

What Gets Analyzed

The tool analyzes your Express.js code to extract:

Routes

• HTTP methods (GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS)
• Route paths (including parameters)
• Route-specific middleware
• JSDoc comments as descriptions

Responses

• Status codes from res.status() calls
• Response types (JSON, send, etc.)
• Response examples from res.json() and res.send()
• Error responses and success responses

Middleware

• Global middleware from app.use()
• Route-specific middleware
• Middleware function names

Output Examples

JSON Output (docs/api-documentation.json)

{
  "info": {
    "title": "API Documentation",
    "version": "1.0.0",
    "description": "Auto-generated API documentation for Express.js application",
    "generatedAt": "2025-08-31T18:06:33.783Z"
  },
  "paths": {
    "/api/users": {
      "get": {
        "summary": "GET /api/users",
        "responses": [
          {
            "status": 200,
            "description": "Success response"
          },
          {
            "status": 401,
            "description": "Unauthorized"
          }
        ],
        "middleware": ["authenticationToken"],
        "security": ["authenticationToken"]
      }
    },
    "/api/users/:id": {
      "put": {
        "summary": "PUT /api/users/:id",
        "responses": [
          {
            "status": 200,
            "description": "Success response"
          },
          {
            "status": 404,
            "description": "Not found"
          }
        ],
        "middleware": ["authenticationToken"],
        "security": ["authenticationToken"]
      }
    }
  },
  "stats": {
    "totalEndpoints": 15,
    "methodCounts": {
      "GET": 5,
      "POST": 6,
      "PUT": 2,
      "DELETE": 2
    },
    "statusCodes": [200, 201, 400, 401, 403, 404, 500],
    "pathsWithParams": 3,
    "middlewareUsage": ["authenticationToken", "validateInput"]
  },
  "tags": {
    "api": {
      "name": "api",
      "description": "Routes under /api",
      "paths": [
        "/api/users",
        "/api/users/:id",
        "/api/auth/signin",
        "/api/auth/signup"
      ]
    }
  },
  "security": {
    "middleware": ["authenticationToken"],
    "description": "Detected security middleware in the application"
  }
}

Markdown Output (docs/README.md)

The tool generates a comprehensive README.md with:

• Overview and metadata
• Table of contents
• Global middleware table
• Detailed route documentation with examples
• Response codes and examples
• Usage instructions

Development Setup

If you want to contribute or modify the tool:

# Clone and install dependencies
git clone <your-repo>
cd create-express-doc
npm install

# Test with the example app
node bin/cli.js example/app.js

How It Works

1. Code Parsing - Uses Babel to parse JavaScript/TypeScript files into an AST
2. Route Discovery - Traverses the AST to find Express route definitions
3. Response Analysis - Analyzes route handler functions to extract possible responses
4. Documentation Generation - Formats the extracted data into JSON and Markdown

Supported Express Patterns

• Standard route definitions: app.get('/path', handler)
• Router-based routes: router.get('/path', handler)
• Multiple middleware: app.get('/path', middleware1, middleware2, handler)
• Chained responses: res.status(200).json(data)
• JSDoc comments for descriptions

Limitations

• Only analyzes static route definitions (not dynamic routes)
• Response examples are extracted from literal values in code
• Middleware analysis is based on function names and call patterns
• Works best with standard Express.js patterns

Contributing

0. Create a new issue if not already.
1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test with various Express.js applications
5. Submit a pull request