Examine source code of Bulk Texter Lite

{
  "manifest_version": 2,
  "name": "Bulk Texter Lite",
  "description": "Send texts with a personal touch, at scale, using the phone number you already have.",
  "version": "3.1.13",
  "browser_action": {
    "default_title": "Bulk Texter Lite",
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://voice.google.com/*"
      ],
      "js": [
        "lib/tools.js",
        "contentScripts/googleVoiceManager.js"
      ],
      "all_frames": true
    },
    {
      "matches": [
        "https://billing.bulktexterpro.com/*"
      ],
      "js": [
        "lib/tools.js",
        "contentScripts/billing.js"
      ],
      "all_frames": true
    }
  ],
  "web_accessible_resources": [
    "contentScripts/injectedModal.html"
  ],
  "icons": {
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{db5a1902-b6e9-43b1-8649-9043ec56b1b7}"
    }
  }
}