Examine source code of MP3Juices

{
  "manifest_version": 2,
  "name": "MP3Juices",
  "version": "1.0",
  "description": "The Add-On allows you to download your most-liked YouTube videos as MP3 files for free.",
  "homepage_url": "https://www.mp3juices.nu/",
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/32.png",
    "default_title": "MP3Juices",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{458c5a14-f501-482f-ac36-f1733935c55d}"
    }
  }
}