Examine source code of Epublifier

{
  "name": "Epublifier",
  "permissions": [
    "downloads",
    "storage",
    "clipboardRead",
    "unlimitedStorage",
    "declarativeNetRequestWithHostAccess",
    "declarativeNetRequestFeedback",
    "scripting"
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "author": "Mao Yu<maoserr@gmail.com>",
  "description": "A tool to convert website based books or list of pages to ePub format to read on your eReader/Kindle/etc.",
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "manifest_version": 3,
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_icon": {
      "16": "images/icon16.png",
      "32": "images/icon32.png",
      "48": "images/icon48.png",
      "128": "images/icon128.png"
    },
    "default_title": "Epublifier"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "js/*.js",
        "js/*.map",
        "css/*.css",
        "*.woff",
        "*.woff2",
        "*.ttf",
        "sidebar.html",
        "sandbox.html"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "epublifier@maoserr.com"
    }
  },
  "background": {
    "scripts": [
      "js/service_worker.js"
    ]
  },
  "version": "3.0.159"
}