It internally uses the "SimpleCaptcha" library to generate the captcha image ,spring-boot for rest services and to provide the captcha ID + captcha expiry mechanisum it uses "expiringmap" from "net.jodah" package. library.
The SimpleCaptcha library is installed as alocal maven repo in the project.
For UI it it uses plain HTML , Jquery and JqueryUI CSS.
Sample View:
