Examine source code of Air Quality Now

{
  "manifest_version": 2,
  "name": "Air Quality Now",
  "description": "Live air quality for any city: European and US AQI, PM2.5, PM10, NO2, ozone and practical advice - free data, no key.",
  "version": "1.4.2",
  "browser_specific_settings": {
    "gecko": {
      "id": "{4f060f3c-f1f3-4a37-9cfc-9730c1f475d4}",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "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"
  },
  "permissions": [
    "storage",
    "https://air-quality-api.open-meteo.com/*",
    "https://geocoding-api.open-meteo.com/*"
  ],
  "browser_action": {
    "default_title": "Air Quality Now",
    "default_popup": "app/popup.html",
    "default_icon": {
      "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"
    }
  }
}