Grégory Viguier

The plugin adds a new tab in your admin bar with simple but useful indications and tools.
<ul>
<li>Displays the number of queries in your page and the amount of time to generate the page.</li>
<li>Displays the php memory usage and php memory limits (constants <code>WP_MEMORY_LIMIT</code> and <code>WP_MAX_MEMORY_LIMIT</code>).</li>
<li>displays the php version and WP version.</li>
<li>Displays <code>WP_DEBUG</code>, <code>SCRIPT_DEBUG</code>, <code>WP_DEBUG_LOG</code>, <code>WP_DEBUG_DISPLAY</code>, and error reporting values.</li>
</ul>
In your site front-end:
<ul>
<li>Lists the template and all template parts used in the current page (template parts added with <code>get_template_part()</code>). Compatible with WooCommerce’s templates.</li>
<li><code>$wp_query</code>: this will open a lightbox displaying the content of <code>$wp_query</code>. Click the lightbox title to reload the value, click outside the lightbox to close it.</li>
</ul>
In your site administration:
<ul>
<li>Admin hooks: lists some oftenly used hooks (like <code>admin_init</code>). The indicator to the right of the line tells you how many times the hook has been triggered by a callback. A “P” means the hook has a parameter: hover it for more details. Click a hook (on its text) to auto-select its code, for example: click admin_init to select <code>add_action( 'admin_init', '' );</code>.</li>
<li><code>$current_screen</code>: displays the value of 4 properties of this object: <code>id</code>, <code>base</code>, <code>parent_base</code>, <code>parent_file</code>.</li>
<li><code>$...now</code>: displays the value of the well-known variables <code>$pagenow</code>, <code>$typenow</code>, and <code>$taxnow</code>.</li>
<li>On a user profile page, <code>$userdata</code>: : this will open a lightbox displaying the user’s data.</li>
</ul>
You can decide who’s gonna use this plugin (go to your profile page for all the settings). This way, the plugin’s items won’t show up to other users (your client for example). 
Also, a new menu item <code>Code Tester</code> will appear. There you are able to do some tests with your code.

Admin Bar Tools

I'm using this wonderfull tool in all my project and ask my studients to use it when they dev for WordPress.

Make a great job

In all my dev sites

This is one of those plugins I use on every WordPress project. The UI/UX is excellent, it's always there in the admin bar, you don't need to load anything. 

It's just a pity it's not updated to the latest WordPress versions. I sure hope this is not abandoned.

Thanks for sharing your work, @greglone.

So useful. Too bad it's not updated

Adds some small development tools to the admin bar.

Sergio Scabuzzo

When running a an audit on a website (yours, a competiror, or client), you can often find yourself going to around ten or more websites to run tests (Inquiries). 
At each of these you then paste the same URL and run it’s test and repeat for each one. Most of these services use the GET HTTP request method. You see these as the ?q= part in <a href="https://duckduckgo.com/?q=ecotechie" rel="nofollow ugc">https://duckduckgo.com/?q=ecotechie</a>.
I decided to write this plugin so I could input a URL once and run all of these tests more easily. No need to hunt down the website addressses or even leave the WordPress admin dashboard!
Features:
<ul>
<li>Use any valid URL for testing, it doesn’t have to be the current site the plugin is installed on.</li>
<li>Add or remove websites to use for tests (Inquirers).</li>
<li>Sortable by filter types like SEO, Speed, Security, etc. Or create your own tags…</li>
</ul>

Inquirer

Run queries of an arbitrary URL on websites that can take these as query parameters.

Admin Bar Tools vs Inquirer