Captcha4J

Captcha4j-core

Tiny java library for generating images and audio-fragments for use in Captcha's.

Features:

Fluent java api for easy customization of the captcha and difficulty level.
Supports internationalization for audio, with multiple English and Dutch voices included (easily extensible)
Minimal number of third party libraries required.

Captcha4j-web-demo

Spring-boot based reference implementation for using Captcha4j-core in a real-world(ish) environment.

Features:

Completely stateless back-end (easy to use horizontally scaled applications) for generating, refreshing and validating captcha's.
Simple-to-read HTML/JS front-end that consumes these webservices.

Usage

Build captcha

ImageCaptcha imageCaptcha = new ImageCaptchaBuilder(200, 50)
        .addAnswer("123abc")
        .addNoise()
        .addBackground()
        .build();
BufferedImage image = imageCaptcha.getImage()

AudioCaptcha audioCaptcha = new AudioCaptchaBuilder()
        .addRandomAnswer()
        .addVoice(Language.NL)
        .addNoise()
        .build();
AudioInputStream stream = audioCaptcha.getAudio().getAudioInputStream();

Example output:

Credits

This project is forked from Stateless-captcha 1.2.1 (https://github.com/sdtool/stateless-captcha), which was in turn based on SimpleCaptcha version 1.2.1 (http://simplecaptcha.sourceforge.net/). There are significant backwards-incompatible changes breaking compatibility with the original works (mix-and-match is not recommended :)).