Open-source implementation of server-side spam filtering of blog comments and forum posts. It's available as a free web service. It's open source, so you can set up your own server if you prefer. It's transparent to end users, and thus perfectly accessible and compatible with all browsers.
Confident Technologies provides free CAPTCHA security software called Confident CAPTCHA, a picture CAPTCHA that stops spam and ...
A spam filtering program that is free for personal use and you have to pay for corporate usage.
A negative captcha has the exact same purpose as your run-of-the-mill image captcha: To keep bots from submitting forms. Image ...
Spam protection plugins for Joomla, WordPress, phpBB3, IP.Board, vBulletin and etc. Protection without CAPTCHA.
reCAPTCHA is a free CAPTCHA service that helps to digitize books, newspapers and old time radio shows. About 200 million CAPTC ...
UniqPin is a free for non-commercial use service which destiny improve ability of interfaces detect a human or a computer oper ...
Securimage is a script for generating complex images and CAPTCHA codes to protect forms from spam and abuse. It can be easily ...
Mollom is a freemium web service to get rid of spam, unwanted content and fake users on your Drupal, Wordpress and Joomla site ...
Easy to use - Nothing stupid your visitors have to type before the form submits.