Crear usuario · Acceder

Animal Captcha, a graphical spam control

Spanish | English


elefanteAnimal Captcha is a PHP program created for web developers who need a secure spam control for HTML forms. It displays a random image picked from a list of animals which only humans can recognize.


  • Nice look: better than an ugly alphanumeric string.
  • Fast: users can identify an animal faster than several mixed letters.
  • Effective: less wrong answers.
  • Secure: the main reason. Some alphanumeric captchas you can find on the Internet are really difficult to be recognized by a bot, but with an animal it's almost impossible!
  • Multi-language: available in some languages, multiple valid names for each animal.


Animal Captcha is divided into two PHP files and one folder containing some images.

  • animal-captcha.php - Returns a random image and saves the name of the animal in a session variable for being checked later.
  • animal-captcha-check.php - It defines animal_captcha_check() function. It returns true if user answer is OK, and false if it's wrong.
  • Folder images - They must be JPG format, a 120x120 px size, showing a very common animal which everybody knows. Names are composed with some words separated by dashes. Each word represents a valid answer for the same animal (eg: cerdo-pig-porc.jpg).

By this way you can easily adding new languages or solving problems about animals which have some different names.


Published under Creative Commons 3.0 license. You can use or modify all you want, but you must attribute the work to the original author: GONZO (Javier González), of Blogs Teoriza.

Sorry about my bad English, i hope it will be useful!

English | Spanish

+2 GONZO 04-05-2008
Categoría: Proyectos Conocimientos Interesante Internet

Artículo escrito por GONZO para Blogs Teoriza.
Animal Captcha, a graphical spam control