Quentin

Allows to define shortcodes for easy replacement. Handy for recurrent copy/paste’s from sites like YouTube or DailyMotion… But not only. You decide! Also allows you not to write un-valid tags that would be stripped out by WordPress (<code><object></code>s for example)
The syntaxt is Shortcodes’ one, but for legacy reasons you can use this syntax : [key:parameter1,parameter2,parameter3…]

Snips

Easy snippet/Shortcode editor plugin for Wordpress

Space X-Chimp

An easy to use, with intuitive interface, WordPress plugin that gives you the ability to easily and safely add your custom code (PHP, HTML, CSS, JavaScript, etc.) to your WordPress website, directly out of the WordPress Admin Area, without the need to have an external editor.
This is a simple and perfect tool to use as your website’s functionality plugin. This is a must have tool for authors and website’s owners. Its purpose is to provide a familiar experience to WordPress users. There is no need for any more editing of the files of your theme or plugins for to add custom code (PHP, HTML, CSS, JavaScript, etc.). Just add your custom code in the field on the plugin page and this plugin will do the rest for you. It will automatically add your custom code to the desired section of your website, without changing any of your theme files and without slowing down your website.
The plugin works completely independently of the theme, so you can use it with any theme. The code you place on the plugin page will be entirely unaffected if you edit the contents of the theme’s files, or even completely change the theme. This is really useful in case of updating theme or plugins, because your custom code would never be overwritten. Your custom code will keep on working, no matter how many times you upgrade or switch your theme and plugins.
On the plugin page you find the code editor powered by CodeMirror. This code editor has options such as syntax highlighting, line numbering, and more. And if you want more options, let us know and we will be happy to add them.
Features
<ul>
<li>Lightweight and fast</li>
<li>Secure code with using clear coding standards</li>
<li>Intuitive interface</li>
<li>Cross browser compatible (work smooth in any modern browser)</li>
<li>Compatible with all WordPress themes</li>
<li>RTL compatible (right to left)</li>
<li>Translation ready</li>
</ul>
Key features include
<ul>
<li>Insert custom PHP/HTML/CSS/JS code into the site</li>
<li>Checks the entered code for fatal errors</li>
<li>Easy disable option for WSOD</li>
<li>Ability to temporarily disable all custom PHP/CSS code</li>
<li>Code syntax highlighting</li>
<li>Line numbering</li>
<li>Active line highlighting</li>
<li>Editor allow for Tab indentation</li>
<li>And much, much more!</li>
</ul>
PRO features include
<ul>
<li>CSS minifier</li>
<li>Manage which HTML/CSS/JS code load on HEAD or FOOTER</li>
<li>Controlling the priority of loading HTML/CSS/JS code</li>
<li>Ability to easily customize the code editor by selecting the desired settings</li>
<li>64 themes for syntax highlighting</li>
<li>Toolbar with useful buttons, such as Undo, Redo, etc.</li>
<li>Ability to use shortcut keys (both Mac and PC) for Search, Replace, etc.</li>
<li>Unlimited number of fields for snippets</li>
<li>Automatic backup of all snippets to a downloadable text file</li>
<li>Separate activation and deactivation of snippets</li>
<li>No ads on the settings page</li>
<li>Well documented</li>
</ul>
<a href="https://www.spacexchimp.com/plugins/custom-code-manager-pro.html" rel="nofollow ugc">Get the PRO version now!</a>
Supported languages
<ul>
<li>PHP</li>
<li>HTML</li>
<li>CSS</li>
<li>JavaScript</li>
</ul>
Translation
This plugin is ready for translation and has already been translated into several languages. But If your language is not available then you can make one. It is also possible that not all existing translations are up-to-date or correct, so you are welcome to make corrections. Many of plugin users would be delighted if you share your translation with the community. Thanks for your contribution!
<ul>
<li>English (default)</li>
<li>Russian (translation by <a href="https://www.instagram.com/milava_kiseleva/" rel="nofollow ugc">Milena Kiseleva</a>)</li>
<li>German (translation by Michael)</li>
<li>Polish (translation by Paweł K.)</li>
<li>Chinese-Taiwan (translation by Gordon Yu)</li>
<li>Spanish (translation by Ramiro Garcés and Patricio Toledo)</li>
<li>Dutch (translation by Peter Leenders)</li>
<li>French (translation by Jean-Michel, Theophil Bethel and Hervé Bouzin)</li>
</ul>
If you want to help translate this plugin, please visit the <a href="https://translate.wordpress.org/projects/wp-plugins/custom-code-manager" rel="nofollow ugc">translation page</a>.
Minimum system requirements:
<ul>
<li><a href="https://wordpress.org">WordPress</a> version 4.9 or higher.</li>
<li><a href="https://secure.php.net" rel="nofollow ugc">PHP</a> version 5.6 or higher.</li>
<li><a href="https://www.mysql.com" rel="nofollow ugc">MySQL</a> version 5.0 or higher.</li>
</ul>
Recommended system requirements:
<ul>
<li><a href="https://wordpress.org">WordPress</a> version 5.0 or higher.</li>
<li><a href="https://secure.php.net" rel="nofollow ugc">PHP</a> version 7.0 or higher.</li>
<li><a href="https://www.mysql.com" rel="nofollow ugc">MySQL</a> version 5.6 or higher.</li>
</ul>
Contribution
Developing plugins is long and tedious work. If you benefit or enjoy this plugin please take the time to:
<ul>
<li><a href="https://www.spacexchimp.com/donate.html" rel="nofollow ugc">Donate</a> to support ongoing development. Your contribution would be greatly appreciated.</li>
<li><a href="https://wordpress.org/support/plugin/custom-code-manager/reviews/#new-post">Rate and Review</a> this plugin.</li>
<li><a href="https://www.spacexchimp.com/contact.html" rel="nofollow ugc">Share with us</a> or view the <a href="https://github.com/ArthurGareginyan/custom-code-manager" rel="nofollow ugc">GitHub Repo</a> if you have any ideas or suggestions to make this plugin better.</li>
</ul>
“Custom Code Manager” is one of the own software projects of <a href="https://www.spacexchimp.com" rel="nofollow ugc">Space X-Chimp</a>.
License
This plugin is licensed under the <a href="http://www.gnu.org/licenses/gpl-3.0.html" rel="nofollow ugc">GNU General Public License, version 3 (GPLv3)</a> and is distributed free of charge. 
Commercial licensing (e.g. for projects that can’t use an open-source license) is available upon request.
Credits
<ul>
<li>The icon of this plugin is a copyrighted image created by the <a href="https://www.spacexchimp.com" rel="nofollow ugc">Space X-Chimp</a> team. (C) All rights reserved.</li>
<li>The banner of this plugin is a copyrighted image created by the <a href="https://www.spacexchimp.com" rel="nofollow ugc">Space X-Chimp</a> team. (C) All rights reserved.</li>
<li>Unless otherwise stated, all images are created by the <a href="https://www.spacexchimp.com" rel="nofollow ugc">Space X-Chimp</a> team and are copyrighted. (C) All rights reserved.</li>
<li><a href="https://codemirror.net/" rel="nofollow ugc">CodeMirror</a> is an open-source project shared under the <a href="https://codemirror.net/LICENSE" rel="nofollow ugc">MIT license</a>.</li>
<li><a href="http://getbootstrap.com" rel="nofollow ugc">Bootstrap</a> by Twitter, Inc. released under the <a href="https://github.com/twbs/bootstrap/blob/master/LICENSE" rel="nofollow ugc">MIT license</a>.</li>
<li><a href="https://github.com/vsn4ik/bootstrap-checkbox" rel="nofollow ugc">Bootstrap-checkbox</a> is a project of <a href="https://github.com/vsn4ik" rel="nofollow ugc">Vasily A.</a>, shared under the <a href="https://github.com/vsn4ik/bootstrap-checkbox/blob/master/LICENSE" rel="nofollow ugc">MIT license</a>.</li>
<li><a href="https://fontawesome.com" rel="nofollow ugc">Font Awesome</a> is an open source-project created by Dave Gandy. Font released under the <a href="http://scripts.sil.org/OFL" rel="nofollow ugc">SIL OFL 1.1 license</a>. Code released under the <a href="http://opensource.org/licenses/mit-license.html" rel="nofollow ugc">MIT License</a>.</li>
</ul>
Links
<ul>
<li><a href="https://www.spacexchimp.com" rel="nofollow ugc">Developer website</a></li>
<li><a href="https://github.com/ArthurGareginyan/custom-code-manager" rel="nofollow ugc">Dedicated plugin page on GitHub</a></li>
<li><a href="https://wordpress.org/plugins/custom-code-manager/">Dedicated plugin page on WordPress.org</a></li>
<li><a href="https://www.spacexchimp.com/plugins/custom-code-manager-pro.html" rel="nofollow ugc">Premium Version</a></li>
</ul>

Custom Code Manager

Easily and safely add your custom code (PHP, HTML, CSS, JavaScript, etc.) to your WordPress website, directly out of the WordPress Admin Area, without …

Snips vs Custom Code Manager