Website DevTools Inspector

Inspect any website with a comprehensive analysis similar to browser DevTools. Get HTTP headers, cookies, response time, metadata, and all loaded resources including scripts, stylesheets, images, and links.

API Reference

GET /devtools

Perform a comprehensive inspection of a webpage by providing its URL.

Example Request

curl "https://your-worker.workers.dev/devtools?url=https://www.cloudflare.com"

Response Structure

success boolean

Indicates if the request was successful

data object

The comprehensive inspection results

data.url string

The requested URL

data.statusCode number

HTTP response status code (e.g., 200, 404, 500)

data.responseTimeMs number

Response time in milliseconds (rounded)

data.headers object

HTTP response headers as key-value pairs. All header names are lowercase.

data.cookies string[]

Array of Set-Cookie header values

data.metadata object

Page metadata

data.metadata.title string | null

Page title from <title> tag

data.metadata.description string | null

Meta description

data.metadata.canonical string | null

Canonical URL if specified

data.scripts string[]

Array of unique absolute URLs of JavaScript files loaded via <script src="...">

data.stylesheets string[]

Array of unique absolute URLs of CSS files loaded via <link rel="stylesheet">

data.images string[]

Array of unique absolute URLs of images from <img src="...">

data.links string[]

Array of unique absolute URLs from <a href="...">. Excludes anchor links (#) and javascript: links.

Example Response

{
  "success": true,
  "data": {
    "url": "https://www.cloudflare.com",
    "statusCode": 200,
    "responseTimeMs": 245,
    "headers": {
      "content-type": "text/html; charset=utf-8",
      "server": "cloudflare",
      "cf-ray": "8a1b2c3d4e5f6g7h-SJC",
      "cache-control": "max-age=3600",
      "content-encoding": "gzip",
      "vary": "Accept-Encoding"
    },
    "cookies": ["__cflb=0123456789abcdef; Path=/; HttpOnly; Secure; SameSite=Lax"],
    "metadata": {
      "title": "Cloudflare - The Web Performance & Security Company",
      "description": "Here at Cloudflare, we make the Internet work the way it should.",
      "canonical": "https://www.cloudflare.com/"
    },
    "scripts": [
      "https://www.cloudflare.com/js/main.js",
      "https://ajax.cloudflare.com/cdn-cgi/scripts/analytics.js"
    ],
    "stylesheets": [
      "https://www.cloudflare.com/css/main.css",
      "https://www.cloudflare.com/css/responsive.css"
    ],
    "images": [
      "https://www.cloudflare.com/img/logo.svg",
      "https://www.cloudflare.com/img/hero-image.png"
    ],
    "links": [
      "https://www.cloudflare.com/products/",
      "https://www.cloudflare.com/plans/",
      "https://developers.cloudflare.com/"
    ]
  }
}

Error Responses

Invalid URL

{
  "success": false,
  "error": "Missing or invalid query parameter: url",
  "code": "INVALID_URL"
}

Fetch Error

{
  "success": false,
  "error": "HTTP 404",
  "code": "FETCH_ERROR"
}

Technical Details

• Built with Hono framework
• Runs on Cloudflare Workers
• Custom User-Agent: Cloudflare-Experiments-DevtoolsInspector/1.0
• Configurable fetch timeout
• Maximum HTML size limit to prevent memory issues
• All relative URLs resolved to absolute URLs
• Response time measured from request start to completion

Inspection Details

Headers

• All response headers are captured
• Header names are normalized to lowercase
• Includes Cloudflare-specific headers (cf-ray, cf-cache-status, etc.)

Cookies

• Extracted from Set-Cookie response headers
• Preserves all cookie attributes (Path, HttpOnly, Secure, SameSite)
• Multiple cookies are returned as separate array entries

Resources

• Scripts: Extracted from <script src="...">
• Stylesheets: Extracted from <link rel="stylesheet" href="...">
• Images: Extracted from <img src="...">
• Links: Extracted from <a href="...">
• All URLs are deduplicated and resolved to absolute URLs

Response Time

• Measured in milliseconds from request initiation to response completion
• Includes network latency and initial content download
• Rounded to the nearest millisecond

Use Cases

• Performance Monitoring: Track response times and identify slow-loading resources
• Security Audits: Analyze headers, cookies, and security configurations
• Asset Analysis: Discover all external dependencies and third-party scripts
• SEO Audits: Inspect metadata and canonical URLs
• Debugging: Investigate website structure and loaded resources
• Competitive Analysis: Understand technology stack and external services used
• Compliance Checks: Verify cookie policies and header configurations

Limitations

• Static HTML fetch for most fields; not a live browser DevTools session
• HTML body is capped at 1MB before parsing
• Cannot inspect authenticated or paywalled pages
• No runtime network waterfall, console, or step-through debugging

Deployment

curl "https://your-worker.workers.dev/devtools?url=https://example.com"

Local Development

cd apps/experiments/website-devtools-inspector
npm install
npm run dev

Test locally:

curl "http://localhost:8787/devtools?url=https://example.com"

Cloudflare Features Used

• Workers - Edge compute runtime
• Fetch API - HTTP requests for headers, HTML, and timing data