
Settings screen
Simple Debug Info Panel for WordPress will enable you to instantly see some “under-the-hood” debugging info for your site. With one click (or none at all), you can see which template is being used, what the post/page ID is, the current screen/viewport size, any categories a post is assigned to, and some more.
Every item’s visibility can be turned on or off, so you have complete control over what will be shown in the infobox.