Developing a theme and wonder, why your changes don't appear front end? Reason might be, WordPress chooses a different template to display content following it's own template hierarchy. But what template is that now? Don't worry, just install this little helper and you'll see a new entry in your menu bar, which always tells you, what file currently gets used. Even more, in comparison to similar plugins it even will tell you about template parts being loaded by get_template_part(), which might save you some more time in development.
The plugin works great right out of the box, integrates well, no settings needed.
And if you wonder about the plugin name: I guarantee, it's easier to remember! ;)
Well done, Barry Kooij!