Captcha is now an important part of a website which protect website from spam bots. Creating a secure captcha is really a hard work and needs more effort. But you can easily save your time and effort with some good and easy to use available php captcha scripts. These are 7 free php captcha scripts which work good.
1. Egglue Semantic CAPTCHA:
This is a nice script which generates intuition based CAPTCHA challenges. In this, visitors are presented 2 sentences and they are asked to type missing verbs in the sentences
2. PHP CAPTCHA:
This is a php library that uses image, audio and visual verification. This library is really useful to prevent SPAMs
reCAPTCHA is a free and powerful captcha script and developed at carnegie mellion university. This is one of the most used php captcha scripts.
4. Easy PHP Captcha:
Quick and Easy to use PHP CAPTCHA script with detailed usage instructions. You can also give it a try.
KCAPTCHA is a very good script to generate strong image captchas. It is free and released under open source. It outputs close and distorted characters which makes it harder for bots to guess. It does not require additional font libraries.
6. PHP Captcha With Refresh:
This is a PHP class that is used to generate and validate captcha. It generates an image with a given width and height display a random validation text with a given length. The generated random text is stored in a session variable for posterior validation. The generated image is obfuscated by a given background image before being served as the current script output in JPEG format.
7. Securimage PHP Captcha:
A free opensource PHP CAPTCHA script for generating complex images and codes to protect from spam and abuse.
These are most used php captcha scripts.