Examine source code of Token Devtools Inspector

{
  "name": "Token Devtools Inspector",
  "description": "Retrieve Authorization header from the request made in your tab. You'll have a faster way to paste or go to JWT.io",
  "version": "1.2.1",
  "manifest_version": 3,
  "devtools_page": "devtools/devtools.html",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "token-devtools-inspector@gmail.com"
    }
  }
}