Examine source code of Geocache Viewer

{
  "manifest_version": 3,
  "name": "Geocache Viewer",
  "version": "2.0.1",
  "description": "Send Geocaching.com pages to Geocache Viewer for easy viewing and parsing.",
  "action": {
    "default_title": "Send to Geocache Viewer",
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "tabs"
  ],
  "host_permissions": [
    "https://www.geocaching.com/*",
    "https://www.cachesleuth.com/gcviewer.html*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{14272297-6e32-4e56-a845-7d641a138805}",
      "strict_min_version": "121.0"
    }
  }
}