Examine source code of Sms77 SMS & Text2Speech

{
  "author": "sms77 e.K.",
  "background": {
    "scripts": [
      "background.bundle.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScripts.bundle.js"
      ]
    }
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "default_locale": "en",
  "description": "Extension for sending SMS & making Text-To-Speech calls via Sms77.io",
  "icons": {
    "16": "icon16.png",
    "19": "icon19.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "manifest_version": 2,
  "name": "__MSG_sms77browser__",
  "options_ui": {
    "browser_style": true,
    "page": "options.html"
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "notifications",
    "storage",
    "tabs",
    "*://gateway.sms77.io/*"
  ],
  "version": "3.0.0",
  "web_accessible_resources": [
    "icon16.png",
    "icon19.png",
    "icon32.png",
    "icon48.png",
    "icon128.png",
    "logo.svg",
    "phoneCollector.html"
  ],
  "applications": {
    "gecko": {
      "id": "firefox@sms77.io"
    }
  },
  "developer": {
    "name": "André Matthies",
    "url": "https://github.com/matthiez"
  }
}