horike

Displays Super Global valiables for the current request.Like $_POST, $_GET, and $_COOKIE. Requires the debug bar plugin.

Debug Bar Super Globals

Hasn't received any updates in 8 years and it STILL WORKS!

Still Works (as of WordPress 5.5)

Displays Super Global valiables for the current request.Like $_POST, $_GET, and $_COOKIE. Requires the debug bar plugin.

10up

Helen Hou-Sandi

Zack Tollman

Debug Bar Cron adds information about WP scheduled events to a new panel in the Debug Bar. This plugin is an extension for 
Debug Bar and thus is dependent upon Debug Bar being installed for it to work properly.
Once installed, you will have access to the following information:
<ul>
<li>Number of scheduled events</li>
<li>If cron is currently running</li>
<li>Time of next event</li>
<li>Current time</li>
<li>List of custom scheduled events</li>
<li>List of core scheduled events</li>
<li>List of schedules</li>
</ul>

Debug Bar Cron

This has been great for checking if WordPress's scheduled events are firing. Good for checking if you need to setup a real cron job or if that real cron job is failing. Very clear presentation.

Great for checking if scheduled events running

Debug Bar Cron adds a new panel to Debug Bar that displays information about WP scheduled events.

Debug Bar Super Globals vs Debug Bar Cron