Examine source code of IP Calculator

{
  "manifest_version": 3,
  "name": "IP Calculator",
  "version": "1.0",
  "description": "Calculate subnets, CIDR, and usable IP ranges.",
  "action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "ip-calculator@pkdiv.mozilla",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}