Examine source code of CIDR Calculator

{
  "manifest_version": 2,
  "name": "CIDR Calculator",
  "version": "4.2",
  "description": "Enter an IPv4 CIDR like 10.0.4.0/22 and instantly see the network, broadcast, netmask, wildcard, host range, usable host count and whether it is a private range. Offline.",
  "icons": {
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ea0efd03-5103-4590-a376-c287629e432b}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_title": "CIDR Calculator",
    "default_popup": "src/popup.html",
    "default_icon": {
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png"
    }
  }
}