Examine source code of One Time Message

{
  "manifest_version": 3,
  "name": "One Time Message - Secure Message",
  "description": "Create one-time secure messages from any page using OneTimeMessage.com.",
  "version": "1.0",
  "action": {
    "default_title": "One Time Message - Secure Message",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "clipboardWrite",
    "https://browser.onetimemessage.com/*"
  ],
  "host_permissions": [
    "https://browser.onetimemessage.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "otm@onetimemessage.com",
      "strict_min_version": "109.0"
    }
  }
}