ctomczyk

Spam Prevention for WP Contact Form 7 and WordPress Comments. 
This plugin adds a small code snippet to determine page scroll and add dynamically a unique token. 
It also supports the “Contact Form 7 Database Addon – CFDB7” and prevents contact form submissions from being saved if validation fails.
If the token doesn’t exists while submitting or call directly API then the incoming request will be rejected.
You can see how it works on <a href="https://www.sitelint.com/contact" rel="nofollow ugc">SiteLint</a> website.

Spam Prevention for Contact Form 7 and Comments

Spam Prevention for WP Contact Form 7 (manage multiple contact forms) and WordPress Comments.

latcomsystems

By default, all images in WordPress posts link to themselves. When a user sees a link, they click on it, and the image shows up by itself for no apparent reason. This has several drawbacks:
<ul>
<li>This is bad for SEO because these links are dead ends.</li>
<li>User experience is diminished due to wasted clicks.</li>
<li>Potential for higher bounce rate since no easy method is provided to get back to the site except for the browser “Back” button.</li>
</ul>
This plugin uses a standards compliant HTML DOM parser (http://sourceforge.net/projects/simplehtmldom/). It does not use regular expressions (regex) to accomplish link removal and therefore will not break your site pages or mess up your theme.
<h3>Support</h3>
<ul>
<li><a href="mailto:sysdev@latcomsystems.com" rel="nofollow ugc">sysdev@latcomsystems.com</a></li>
</ul>

LCS Image Nolink

New images inserted into posts will have no links by default.  Existing self-links on all images are removed before the post content is shown.

Spam Prevention for Contact Form 7 and Comments vs LCS Image Nolink