You can use this script to add captcha to your application for preventing bots and unwanted applications to fill up your forms on site. Very easy to setup and modifiable, you can even add new fonts to it. You can also use your custom font such as popular animal font that will prevent even from OCR applications recognizing the characters. Random rotation of characters makes it very hard for software applications to recognize the characters. And on the fly word creation makes this captcha UNBREAKABLE. Each time a new word is shown to the user and never repeats.