Top 7 verification-code open source projects

可扩展java验证码工具类。支持字母，中文，数字运算；同时可配置验证码尺寸，背景色，干扰项

Go Captcha is a behavioral captcha, which implements the generation of random verification text and the verification of click position information.

基于LibSVM实现的验证码识别，通过对验证码图片进行二值化、去噪、切割等处理后，对每个字符进行识别。识别过程采用LibSVM来实现。可用于识别网站登录的验证码。

Customisable OTP view and Passcode view

web dynamic validation code generator 动态web校验码图片生成

Verify Solidity smart contracts on Etherscan

A customisable verification code view to capture OTPs