CAPTCHA is designed to recognize the difference between a bot and human and sometimes even malicious software to provide the security to your system. If you want to prevent the entry of bots into your website then you can start using the CAPTCHA as it is the smartest way to stop it.
Check out some tutorials below.
1a. jQuery AJAX PHP Captcha
1. QapTcha: jQuery captcha system with jQuery & jQuery UI
This is an easy-to-use, simple and intuitive captcha system. It needs human action instead of to read a hard text and it is a very lightweight jQuery plugin.
2. jQuery Fancy Draggable Captcha
Here is a jQuery example for a captcha in a registration form. In order to pass the “Are you human” test, the user has to drag the numbers from 1 to 6 into order.
3. reCaptcha style Captcha with JQuery and PHP
This tutorial is about to creating a captcha same as recaptcha. Create your own recaptcha style captcha with PHP and jQuery.
4. jQuery Advanced Ajax validation with CAPTCHA
jQuery offers a plugin called validate which will allow you to create stunningly user friendly sign up forms, login addresses, contact forms and much more. In this tutorial I’m going to teach you how to create a signup form with advanced AJAX validation and CAPTCHA.
5. s3Capcha jQuery plugin
It is an advanced plugin script that asks for choosing the correct image instead of asking to recognize the difficult text.
6. Ajax Stylish Captcha and Contact Form using JQuery and PH
This tutorial is about AJAX based contact form with jQuery validation and AJAX based captcha.
7. Ajax Fancy Captcha
Ajax Fancy Captcha is a jQuery plugin that helps you protect your web pages from bots and spammers.
8. 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.
is a plugin, that protects your site from robots using jQuery. To unlock captcha you need to drag letters into baskets and get some simple word, or site name, which was typed in options.
10. Sexy Captcha – Drag-and-Drop Ajax Captcha
Sexy Captcha is a truly ajaxified, sexy captcha module. It’s visually stimulating, functional and returns immediate feedback on whether the user’s answer was correct.