Examine source code of Stack Spy

{
  "manifest_version": 2,
  "name": "Stack Spy",
  "short_name": "Stack Spy",
  "description": "Detect the full tech stack of any website — frameworks, analytics, CDN, payments and more.",
  "version": "2.2.0",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    },
    "default_title": "Stack Spy"
  },
  "background": {
    "scripts": [
      "config.js",
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "exclude_matches": [
        "*://builtwith.com/*",
        "*://*.builtwith.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle",
      "all_frames": false
    }
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "alarms",
    "webRequest",
    "http://127.0.0.1/*",
    "http://localhost/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "icons/*",
    "fingerprints_lite.json"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "stackspy@stack-spy.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "browsingActivity",
          "websiteContent"
        ],
        "optional": [
          "technicalAndInteraction"
        ]
      }
    }
  }
}