Emoji Captcha Verification System – eCaptcha
An easy and client-side captcha verification system that requests the user to pick the correct emoji in order to prove human.
JavaScript & CSS Captcha
DOOM Video Game Captcha In JavaScript
A DOOM captcha library that completes captcha verification by killing a specified number of enemies.
Image Rotation Captcha (Human Verification) Library – RVerify.js
RVerify.js is a creative captcha library to determine whether or not the user is human by rotating an image.
Minimal Math Captcha JavaScript Library – jCaptcha.js
jCaptcha.js is a lightweight, vanilla JavaScript plugin which creates a simple, random, canvas based math captcha to protect against spam.
Simple Numeric Captcha In Pure JavaScript – JS-Captcha
JS-Captcha is a native JavaScript library that creates a simple numeric captcha in your HTML form to prevent against spam.