A Simple PHP CAPTCHA Script
This is one of the easiest CAPTCHA scripts you will ever use. While it doesn’t obscure the text, it will serve its purpose well for many people who need a low-level CAPTCHA solution. This script requires little-to-no setup. The only dependency is the PHP GD library. It can be as simple as this to use, but it is also configurable: More details and an example on our website.