Examine source code of Currency Converter nc

{
  "manifest_version": 2,
  "name": "Currency Converter",
  "version": "1.0",
  "description": "A simple currency converter utility.",
  "permissions": [
    "https://api.exchangerate-api.com/"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "32": "icons/logo_32.png",
      "64": "icons/logo_64.png",
      "128": "icons/logo_128.png"
    }
  },
  "icons": {
    "32": "icons/logo_32.png",
    "64": "icons/logo_64.png",
    "128": "icons/logo_128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{57f5fb35-a19a-4f50-9d58-0679f92055fd}"
    }
  }
}