gh0stpr3ss

No more need for captchas, making your readers jump through hoops in order to comment. Instead, activate this plugin and let a simple hidden honeypot input field catch spam bots, which will fill out all fields in the form (even our hidden honeypot field). If that honeypot field isn’t empty, the comment won’t process, effectively nuking most spam comments.
I also made sure that the id of the field is utilizing a random string of letters and numbers every time the page is loaded (ie: 34rscsDW37g8gf) so that spam bots can’t target a specific id name in order to bypass it, making it harder for the bots to win.
Installation is dead simple, just activate the plugin and you’re done. No other steps required on your end, the plugin handles everything.
<h3>Additional info</h3>
The basic structure of this plugin was cloned from the <a href="https://github.com/tommcfarlin/WordPress-Plugin-Boilerplate" rel="nofollow ugc">WordPress-Plugin-Boilerplate</a> project.
This plugin supports the <a href="https://github.com/afragen/github-updater" rel="nofollow ugc">GitHub Updater</a> plugin, so if you install that, this plugin becomes automatically updateable direct from GitHub. Any submission to WP.org repo will make this redundant.

Honeypot Comments

Plugin to stop most comment spam by adding in a simple honeypot for spam bots to get caught in.

WP Chill

Silkalns

Cristian Raiber

A very useful plugin for everyone using WordPress. Adds reCaptcha security to the WordPress login form, register form and comment form. This plugin could help your blog get rid of a lot of spam comments or brute-force attacks.
Nothing gets passed it if the reCaptcha doesn’t validate.
A few notes about the plugin:
<ul>
<li>Supports audio or image captcha types</li>
<li>Can generate the reCaptcha image / audio type in a number of predefined languages</li>
<li>Adds reCaptcha protection to the WordPress login form</li>
<li>Adds reCaptcha protection to the WordPress register form</li>
<li>Adds reCaptcha protection to the WordPress comment form</li>
<li>Adds reCaptcha protection to the WordPress recover password form</li>
</ul>

Uber reCaptcha

This plugin adds the reCaptcha form to the WordPress login form, recover password form, register form and comment form.

Honeypot Comments vs Uber reCaptcha