kaptcha is a modern version of the simple captcha project.
This repo is the clone of https://code.google.com/p/kaptcha/

<dependency>
  <groupId>com.youkol.support.kaptcha</groupId>
  <artifactId>kaptcha</artifactId>
  <version>2.3.2</version>
</dependency>

kaptcha-spring-boot-starter

Please see more information about this project.
https://code.google.com/p/kaptcha/
thanks.