Jonathan Fleury

This is a “draggable” captcha. Images have to be dragged into ascending order.
IMPORTANT : This pluggin require PHP 5.4 and GD extension.

Guroot Captcha

This is a "draggable" captcha. Images have to be dragged into ascending order.

atitan

Math Quiz generates dynamic math problem in the comment form to beat spam robots and supports flexible form style customization.
Demo website: https://atifans.net/ (with Supercache and AJAX comment form enabled)
For PayPal donation, please use this email address: info a.t atifans.net
Features:
<ul>
<li>Dynamic problems prevent spam robots from posting unwanted content.</li>
<li>Quiz form inserted using AJAX for better compatibility with HTML cache plugins.</li>
<li>Form style and position can be customized in the control panel.</li>
<li>Trackbacks and Pingbacks are checked with DNS queries to avoid abuse.</li>
<li>Optional login page protection.</li>
</ul>
Translators:
<ul>
<li>SLV-es (Spanish)</li>
<li>Joao Paulo (Portuguese)</li>
</ul>

Math Quiz

Math Quiz generates dynamic math problem in the comment form to beat spam robots.

Guroot Captcha vs Math Quiz