Examine source code of WebTrackr

{
  "manifest_version": 2,
  "name": "WebTrackr",
  "description": "Webtrackr monitors webpages for changes and alerts you via Email, Slack or Telegram on detecting a change.",
  "version": "1.0.0",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.5.1.min.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "all_frames": false
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/logo16.png",
      "32": "images/logo32.png",
      "48": "images/logo48.png",
      "128": "images/logo128.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "notifications",
    "https://app.webtrackr.io/*",
    "https://webtrackr.io/*"
  ],
  "web_accessible_resources": [
    "modal.html"
  ]
}