antispam

tirreno is an open-source framework for building sovereign security, compliance and fraud prevention applications. Detect account takeovers, cyberfraud and business logic abuse inside your product.

Google ReCAPTCHA v3 for Symfony

„... another popular solution to fight spam is Antispam Bee“ – Matt Mullenweg, Q&A WordCamp Europe 2014

PHP spam protection. CAPTCHA-free and reCAPTCHA alternative. Powered by background scoring without challenging website visitors.

YOURLS plugin: antispam plugin. Checks URL against major DNS black lists and removes all crap.

Extension:Moderation is a powerful anti-spam extension for MediaWiki CMS. It protects small/medium wikis against vandalism by sending all edits/uploads from new users to moderation.

Libre antispam system with human authentication.

A lightweight plugin that protects email addresses from email-harvesting robots by encoding them into decimal and hexadecimal entities.

Caldera Forms Anti Spam WordPress plugin. This adds Google's reCAPTCHA field to your Caldera Form.

A complete, more than an RBL Management System

Automatic updating of the comment blacklist in WordPress with antispam keys from GitHub.

WP Anti-Spam

SpamTagger

Anit-spam extension for Yii framework.

Antispam extension for MediaWiki.

CleanTalk Anti-Spam extension for phpbb v3.1.X & v3.2.X & v3.3.X

XenForo anti-spam addon.

Joomla 3+ Anti-Spam by CleanTalk

Module for any CMS

IPS Community Suite 4.0 (IP.Board) anti-spam extension.