Brian Alexander

Adds the current page’s template name to the admin bar.
Because this plugin reveals potentially sensitive information about the active theme, it is recommended for development environments only, and should not be enabled on a production site.

What Template

Adds the current page's template name to the admin bar.

Mike Selander

Simple Frontend Template Display will show the name of the template that you’re using in the toolbar when you’re in the frontend of your website. You can use this to keep track of the various templates you’re using without having to hop into the edit screen every time you want to check a template.
All you have to do to get this working is to install the plugin. It will then automatically show up in the toolbar on all pages on your site.

Simple Frontend Template Display

Adds an admin toolbar menu item that displays the current page template.

What Template vs Simple Frontend Template Display