SKSDEV

Allow PHP Execute Run PHP code inserted into WordPress posts and pages and Text Widget 
also you can add php code in your post or page title section.
The PHP code runs as the page is sent to the browser. Output of the PHP code is published 
 directly onto the post , page or widget section where the PHP code is located. 
you can be activated without any fear.
Examples of use:
<ul>
<li>Use the php code on your page, post ,default text widget ,page title or post title
</li>
</ul>

Allow PHP Execute

Executes PHP code on WordPress post ,page and on default Text Widget

RMWebsec

Like a normal text widget this allows you to easily post text and HTML, but 
now you can execute PHP too! 
This makes merging with other themes easier.
!IMPORTANT! You must use tags for the code to be 
recognized.

PHP-Widgetify

Execute HTML, Text or PHP fast and easy with this Widgetify-widget.

Allow PHP Execute vs PHP-Widgetify