Here are six jQuery plugin that helps you protect your web pages from bots and spammers.
MotionCAPTCHA
In order to submit the form, you’ll need to copy the shape in the box, as indicated.
Ajax Fancy Captcha
Captcha’s security level is medium, with the emphasis on nice looking and user friendly qualities while still offering reasonable protection from unwanted “guests”. Basic design and its elements are easy to change and customize (take a look at file structure for more information).
qaptcha
Easy-to-use captcha implementation, need human action instead of hard to read text and lightweight jQuery plugin.
s3Capcha
The s3Capcha jQuery plugin is made by an example of WebDesignBeach Ajax Fancy Captcha.
Coding a Minimalist Contact Form with CAPTCHA Spam Protection
Website contact forms are almost a staple of the modern day Internet. Most company websites will have a small contact form where visitors can share their thoughts or suggestions to the webmaster. But there are also so many bots available that these forms can become plagued with spam.
jQuery Real Person
This plugin is designed to help overcome automated form submission by requiring a “real person” to identify text made up of dots. The entered value is compared on the server with the generated value to determine whether processing should continue.