Examine source code of to kindle

{
  "manifest_version": 3,
  "name": "to kindle",
  "version": "2.0.1",
  "description": "Extension that sends the current web article to kindle using the user's kindle device's email address",
  "permissions": [
    "activeTab",
    "downloads",
    "notifications",
    "storage",
    "contextMenus",
    "scripting"
  ],
  "action": {
    "default_popup": "index.html",
    "default_title": "to kindle"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "kindle16.png",
    "32": "kindle32.png",
    "48": "kindle48.png",
    "96": "kindle96.png",
    "120": "kindle120.png",
    "128": "kindle120.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "tokindle@firefox.extension",
      "strict_min_version": "109.0"
    }
  }
}