Add Hashcash spam protection to Contact Form 7.
Kick spam with a highly advanced email validation in comment forms, user registration and contact forms using Mailgun's Email validation service.
Asks commenters to complete a simple CAPTCHA if they don't have a previously approved comment, or if Akismet thinks their comment is spam.
BotSmasher stops spam by checking comments and registrations against the BotSmasher API.
To protect your Blog from automated spambots, this plugin adds invisible formfields to your comment form.
Spam BLIP stops comment spam before it is posted, using DNS blacklists, existing comments marked as spam, and user defined lists.
Keep Your Site Happy, add Khush Captcha Anti-SpamBot Technology to your WordPress Registration and Comment Forms.
minteye - STOP SPAM, MAKE MONEY!
Provides a configurable limit on the length of comments left in the comment form, with a dynamically updated character count displayed for the user.
Todd Lahman's comment spam blocking plugin that blocks automated spam with zero false positives.
Adds CAPTCHA anti-spam methods to WordPress on the forms for comments, registration, lost password, login, or all. For WP, WPMU, and BuddyPress.
Simple question that blocks most spambots (and paid robots) by making them answer a common sense question
OSE Firewall™ Security - part of Better WordPress Security™ Project, a WordPress Firewall plugin to protect your website against hacking, virus an
REPLACEMENT of the original Simple Trackback Validation Plugin from Miachel. Performs a simple but very effective test on all incoming trackbacks in o
Bloquea el spam de todo tipo de robots con un captcha que es invisible para los usuarios de tu web o blog.
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