Kaptcha

Captcha or Completely Automated Public Turing test to Tell Computers and Humans Apart is a technology commonly used on blogs and website to act as a security check that makes sure real users are accessing that page. While it is true that they are mostly a nuisance when you are searching for information on the web, in reality, they come with several advantages.

For starters, they can make online shopping more secure for both the customers filling in their data and the sellers who can reduce the numbers of fake or spam numbers. Speaking of spam, captchas have the role of preventing mal-intended users from making inappropriate comments on various posts anonymously.

Kaptcha is very easy to setup and use and the default output produces a captcha that should be fairly hard to bust. If you would like to change the look of the output captcha, there are several configuration options and the framework is modular so you can write your own morphing code.

Basic use of captcha in your web app is quite easy. All you need to do is add the jar to your project, make a reference to the captcha servlet in your web.xml and then check the servlet session for the generated captcha value and compare it to what the user submits on your form.