Jesper van Engelen

The Sidebars & Widgets extension for the Debug Bar shows you all you need to know about the sidebars and widgets on the current page. It shows the sidebars displayed and the widgets displayed in them, and tells you whether all widgets in the sidebar were actually displayed.
This plugin allows you to analyze the behaviour of your WordPress sidebars and wigets, and is aimed at WordPress developers.
<blockquote>
This plugin is an extension to the <a href="https://wordpress.org/plugins/debug-bar/" rel="ugc">Debug Bar plugin</a>, which is required for this plugin to work.
</blockquote>
This plugin integrates nicely with <a href="https://wordpress.org/plugins/content-aware-sidebars/" rel="ugc">Content Aware Sidebars</a>, telling you what sidebars were replaced and merged. It is an essential plugin if you use Content Aware Sidebars with a big number of sidebars.

Debug Bar – Sidebars & Widgets

Debug Bar extension that adds information about the sidebars and widgets on the current page. Integrates with Content Aware Sidebars plugin.

Taylor Dewey

Debug Bar Post Meta adds a pane to the debug bar with information about post meta for the current post. 
This plugin requires the Debug Bar installed and activated in order to help you.
<h3>TODO</h3>
<ul>
<li>Only load the menu when viewing a single post either in admin or front-end.</li>
</ul>

Debug Bar Post Meta

Very simple extention to the debug bar to get a list of post meta for the current post

Debug Bar – Sidebars & Widgets vs Debug Bar Post Meta