Luigi Cavalieri

RedBrick is able to block most of the automated spam comments a WordPress blog receives daily.
It is based upon a score system that ensures spam comments are blocked as soon as possible, so as to minimise the number of checks each comment must go through. When in doubt, RedBrick always holds the comment in the moderation queue. Comments identified as spam, however, never reach the database.
As a last resource in discerning the kind of comment under examination, RedBrick takes account also of the comment author’s history.
The plugin is designed to work on low-to-medium traffic blogs.

RedBrick

Simple anti-spam plugin for WordPress blogs.

shawfactor

Why should your users prove that they’re humans by filling out captchas? Let bots prove they’re not bots with the <a href="http://lhero.org/plugins/lh-zero-spam/" rel="nofollow ugc">LH Zero Spam plugin</a>.
LH Zero Spam blocks registration spam and spam in comments automatically without any config or setup. Zero Spam was initially built based on the work by <a href="http://davidwalsh.name/wordpress-comment-spam" rel="nofollow ugc">David Walsh</a>, but enhanced with simpler code base and unobtrusive JavaScript.
Major features in LH Zero Spam include:
<ul>
<li>No captcha, because spam is not users’ problem</li>
<li>No moderation queues, because spam is not administrators’ problem</li>
<li>Blocks spam registrations & comments with the use of JavaScript</li>
<li>Blocks buddypress spam registrations with the use of JavaScript</li>
<li>Blocks woocommerce spam orders with the use of JavaScript</li>
</ul>
Like this plugin? Please consider <a href="https://wordpress.org/support/view/plugin-reviews/lh-zero-spam/" rel="ugc">leaving a 5-star review</a>.
Love this plugin or want to help the LocalHero Project? Please consider <a href="https://lhero.org/portfolio/lh-zero-spam/" rel="nofollow ugc">making a donation</a>.

LH Zero Spam

The plugin itself works perfectly and if you like lightweight unobtrusive solutions it is the way to go



Ben Marshalls commenty is unhelpful

Zero Spam makes blocking spam comments and registrations easy.

RedBrick vs LH Zero Spam