webvitaly

<ul>
<li><a href="http://web-profile.net/wordpress/plugins/" title="WordPress Pro plugins" rel="nofollow ugc">WordPress Pro plugins</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/info/" title="Info plugin page" rel="nofollow ugc">Info plugin</a></li>
<li><a href="http://web-profile.net/donate/" title="Support the development" rel="nofollow ugc">Donate</a></li>
<li><a href="https://github.com/webvitalii/info" title="Fork" rel="nofollow ugc">GitHub</a></li>
</ul>
Plugin shows in the admin bar: 
* the number of SQL queries during the WordPress execution 
* the amount of time in seconds to generate the page 
* memory load
Admin bar can be enabled in your profile: <code>"Users => Your Profile => Show Admin Bar"</code>. 
This information also added to the bottom of the source code as HTML comment.
<h4>Useful:</h4>
<ul>
<li><a href="https://wordpress.org/plugins/page-list/" title="list of pages with shortcodes" rel="ugc">“Page-list” – show list of pages with shortcodes</a></li>
<li><a href="https://wordpress.org/plugins/iframe/" title="embed content" rel="ugc">“Iframe” – embed content</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/" title="WordPress Pro plugins" rel="nofollow ugc">WordPress Pro plugins</a></li>
</ul>

info

Plugin shows in the admin bar the number of SQL queries, the amount of time in seconds and memory load.

Eugen Bobrowski

This is tool that help developers and administrators easier getting information.
The debug bar is available on front side for everyone if WP_DEBUG is true. If you are admin you can open bar on any page. Hover the mouse cursor to bottom right corner and click on
<h4>Features:</h4>
<ul>
<li>Implementation time counter</li>
<li>Queries counter</li>
<li>Queries list (sortable)</li>
<li>Memory counter</li>
<li>Segment checker</li>
<li>Cron jobs information</li>
<li>WP_Cache counter</li>
<li>phpinfo() window</li>
<li>References menu</li>
<li>Image Puller that provide pull missed images from production to develop site</li>
</ul>
Implementation time counter
It count the time from plugin loaded action to debug bar. 
It does not consider processes that implement before and during the plugins are loading.
Queries counter
It count all what is queried via $wpdb object.
Queries list
It show all what is queried via $wpdb object.
The <code>SAVEQUERIES</code> constant must be defined as <code>true</code>.
Memory counter
Returns the amount of memory, in bytes, that’s currently being allocated to your PHP script.
Segment checker
Also you can check any segment of your code.
<pre><code>do_action('check_segment', 'segment_1');

//do somethisng

do_action('check_segment', 'segment_1');
</code></pre>
The code below returns in debug bar new item like this:
<blockquote>
segment_1: 14.14/3/1
</blockquote>
The digits there ara time, queries and how many times this code was implemented.
References menu
The default one item of this menu is Errors. It shows notices and warnings including case when <code>WP_DEBUG</code> is false.
And also you can easy add your item to this menu and print there any var_dump or anything else.
<pre><code>add_filter('wp_debug_refs', 'my_debug_tool_ref');

function my_debug_tool_ref ($refs) {

 global $post;

 $refs['my_ref_id'] = array(
 'title' => 'My ref',
 'content' => 'My ref' . var_export($post, true),
 );
 return $refs;
}
</code></pre>

Debug Tool

Show helpful debug bar at front and admin side. Tool for developers.

info vs Debug Tool