Examine source code of SentRadar.com

{
  "manifest_version": 3,
  "name": "SentRadar.com",
  "description": "Email tracking with read receipts",
  "version": "1.0.0",
  "icons": {
    "16": "/icons/icon-16.png",
    "48": "/icons/icon-48.png",
    "128": "/icons/icon-128.png"
  },
  "permissions": [
    "storage",
    "scripting",
    "webNavigation"
  ],
  "host_permissions": [
    "*://mail.google.com/*",
    "https://sentradar.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "pageWorld.js"
      ],
      "matches": [
        "https://mail.google.com/*"
      ]
    }
  ],
  "action": {
    "default_title": "SentRadar.com",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b8a1e3c0-8f7a-4d2b-9e6c-1a5b3d7f2e8a}",
      "data_collection_permissions": {
        "required": [
          "personallyIdentifyingInfo"
        ],
        "optional": [
          "technicalAndInteraction"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}