Examine source code of Nod Header

{
  "manifest_version": 3,
  "name": "Nod Header",
  "version": "1.0.0",
  "description": "Add, override and remove HTTP request and response headers. Switch profiles, filter by URL, keep it all local.",
  "browser_specific_settings": {
    "gecko": {
      "id": "nod-header@nodheader.dev",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "action": {
    "default_popup": "popup/popup.html",
    "default_title": "Nod Header",
    "default_icon": {
      "16": "assets/icon-16.png",
      "32": "assets/icon-32.png",
      "48": "assets/icon-48.png",
      "128": "assets/icon-128.png"
    }
  },
  "background": {
    "scripts": [
      "background/service-worker.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'none'; style-src 'self'; img-src 'self'; connect-src 'none'; base-uri 'none'; frame-src 'none'"
  },
  "permissions": [
    "declarativeNetRequest",
    "storage",
    "webRequest",
    "webRequestBlocking"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "icons": {
    "16": "assets/icon-16.png",
    "32": "assets/icon-32.png",
    "48": "assets/icon-48.png",
    "128": "assets/icon-128.png"
  },
  "commands": {
    "toggle-enabled": {
      "suggested_key": {
        "default": "Alt+Shift+H",
        "mac": "Alt+Shift+H"
      },
      "description": "Turn Nod Header on or off"
    }
  }
}