Karrde

Includes a file’s contents in the widget. Quick and dirty, all this does is use the PHP include function to include the specified file in the widget. There is NO checking done whatsoever on the file, so use it at your own risk. I wrote this because I couldn’t find a widget to do this ? plugins exist for using include in posts and pages, but not in widgets.

Include Widget

Includes a file's contents in the widget.

Stefano Lissa

Include Me helps to include in posts or pages external files usually to be shared 
between different posts or pages or that contains PHP or other code that can be 
compromised by the visual editor.
The use is immediate: the shortcode [includeme] is all that you need (see the documentation 
on <a href="https://www.satollo.net/plugins/include-me" rel="nofollow ugc">Include Me official page</a>).
The best way to use it is to include functionalities 
written in external PHP that will be rendered in post body or to include pieces of 
javascript that will be hard to add with WordPress editor.
Inclusions can be rendered with IFRAME if needed to create boxes that display 
external web pages.
This plugin is made of few line of code, ultralite!
Other plugins by Stefano Lissa:
<ul>
<li><a href="https://www.satollo.net/plugins/hyper-cache" rel="nofollow ugc">Hyper Cache</a></li>
<li><a href="https://www.thenewsletterplugin.com" rel="nofollow ugc">Newsletter</a></li>
<li><a href="https://www.satollo.net/plugins/header-footer" rel="nofollow ugc">Header and Footer</a></li>
<li><a href="https://www.satollo.net/plugins/thumbnails" rel="nofollow ugc">Thumbnails</a></li>
</ul>
<h4>Translation</h4>
You can contribute to translate this plugin in your language on <a href="https://translate.wordpress.org" rel="nofollow ugc">WordPress Translate</a>

Include Me

Include Me helps to include any external file (textual, HTML or PHP) in posts or pages.

Include Widget vs Include Me