WhizKins

WPSimpleInsert is a plugin to insert custom code in your blog posts. It includes options to either add the code above 
or below post content.
Features:
<ul>
<li>Add custom HTML/PHP/JavaScript to your posts.</li>
<li>Ability to add custom code above or below post content.</li>
<li>Options to hide the code from certain pages like the home page and category and archives pages.</li>
</ul>

WP Simple Insert

A plugin to insert custom HTML or PHP code in your posts. Includes options to insert before or after post content.

pixelgrade

vlad.olaru

George Olaru

With <a href="https://github.com/pixelgrade/pixcodes" rel="nofollow ugc">PixCodes</a> you can have a shortcode insert interface for the WordPress Classic Editor.
PixCodes is intended for Classic Editor and TinyMCE workflows. It does not add a block editor interface.
The awesome part is that you can filter any shortcode parameters or overwrite any shortcode template with your theme.
Note: this plugin does not add any style to the output of shortcodes.
We believe that shortcodes functionality should be offered by a plugin and the style should be provided by themes.
Here is a <a href="http://github.com/pixelgrade/pixcodes/blob/master/README.md" rel="nofollow ugc">detailed documentation</a> about how you can configure some plugin settings and output.

PixCodes

PixCodes offers a Classic Editor interface for inserting Pixelgrade shortcodes.

WP Simple Insert vs PixCodes