Examine source code of online2convert.com

{
  "name": "Online File Converter - online2convert.com",
  "description": "Online2Convert is an online service that supports the conversion to multiple formats, completely free and easy to use.",
  "version": "1.0",
  "manifest_version": 2,
  "browser_action": {
    "default_popup": "/popup.html",
    "default_icon": {
      "16": "/images/icon16.png",
      "32": "/images/icon32.png",
      "48": "/images/icon48.png",
      "128": "/images/icon128.png"
    }
  },
  "icons": {
    "16": "/images/icon16.png",
    "32": "/images/icon32.png",
    "48": "/images/icon48.png",
    "128": "/images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c6a0d045-0ea8-4f55-a900-5d0532e50052}"
    }
  }
}