WordPress Zero Spam blocks registration spam and spam in comments automatically without any additional config or setup. Just install, activate, and enjoy a spam-free site.
Zero Spam was initially built based on the work by David Walsh.
Major features in WordPress Zero Spam include:
No captcha, spam isn’t a users’ problem
No moderation queues, spam isn’t a administrators’ problem
Blocks 99.9% of spam registrations & comments
Supports caching plugins to help provide great performance
Blocks spammy IPs from ever seeing your site
Extend the plugin with action hooks
Theme & plugin integration for any form on your site
Optional logging, so you can see who’s trying to spam
Advanced settings for complete control
Upload the zero-spam folder to the /wp-content/plugins/ directory
Activate the plugin through the ‘Plugins’ menu in WordPress