captcha - Go package captcha implements generation and verification of image and audio CAPTCHAs.

•    Go

Package captcha implements generation and verification of image and audio CAPTCHAs.A captcha solution is the sequence of digits 0-9 with the defined length. There are two captcha representations: image and audio.

negative-captcha - A plugin to make the process of creating a negative captcha in Rails much less painful

•    Ruby

A negative captcha has the exact same purpose as your run-of-the-mill image captcha: To keep bots from submitting forms. Image ("positive") captchas do this by implementing a step which only humans can do, but bots cannot: read jumbled characters from an image. But this is bad. It creates usability problems, it hurts conversion rates, and it confuses the shit out of lots of people. Why not do it the other way around? Negative captchas create a form that has tasks that only bots can perform, but humans cannot. This has the exact same effect, with (anecdotally) a much lower false positive identification rate when compared with positive captchas. All of this comes without making humans go through any extra trouble to submit the form. It really is win-win. In a negative captcha form there are two main parts and three ancillary parts. I'll explain them thusly.

EasyOCR - Java OCR 识别组件（基于Tesseract OCR 引擎）。能自动完成图片清理、识别 CAPTCHA 验证码图片内容的一体化工作。Java Image cleanup, OCR recognition component (based Tesseract OCR engine, automatically cleanup image and identification CAPTCHA verification code picture content)

EasyOCR is a Java language using OCR recognition engine (based Tesseract). By means of a few simple API, the Java language can be used to complete the picture content identification work. And integrated image cleanup, recognition CAPTCHA image, bill notes and other content integration efforts. EasyOCR engine supports plugin programming, ETD templates support, provide a graphical ETD template design tools (EasyTemplateDesigner GUI). EasyOCR not only provide services for consumers, but mainly oriented to provide localized development SDK integration with C/S, B/S and Android mobile terminal native integration projects.

SimpleCaptcha - Java library for generating CAPTCHA challenge/answer pairs

•    Java

An easy to implement CAPTCHA framework to generate image and audio challenges, for Java 1.5 and Java 6.

JCAPTCHA - java implementation of the Captcha project

•    Java

JCAPTCHA stands for Java Completely Automated Public Test to tell Computers and Humans Apart. The open source java framework for captcha definition and integration. It supports multi-type challenge (text, sound, image).

base64Captcha - golang base64-captcha supports digits, numbers,alphabet, arithmetic, audio and digit-alphabet captcha

•    Go

SetCustomStore sets custom storage for captchas, replacing the default memory store. This function must be called before generating any captchas. NewMemoryStore returns a new standard memory store for captchas with the given collection threshold and expiration time in seconds. The returned store must be registered with SetCustomStore to replace the default one.

Captcha Control

•    ASPNET

Captcha Control (C#) allows users to add a captcha to an asp.net page. The control supports declarative settings of fontsize, font family, color, captcha length, background image, character set, success, error and buttons' text. Supports audio - reading out the captcha text.

ASP Security Image Generator (CAPTCHA)

ASP Security Image Generator (CAPTCHA) a web-based dynamic image processing script for CAPTCHA test. Image files and components not required. Changable text and background color. Enable or disable image distortion. It is written for ASP in VBScript.

rucaptcha - Captcha gem for Rails Application. No dependencies. No ImageMagick, No RMagick.

•    C

This is a Captcha gem for Rails Applications which generates captcha image by C code.

captcha - A captcha library that generates audio and image CAPTCHAs.

•    Python

A captcha library that generates audio and image CAPTCHAs.This is the APIs for your daily works. We do have built-in voice data and font data. But it is suggested that you use your own voice and font data.

MVC3 captcha | MVC captcha

MVC captcha and MVC invisible captcha. Ajax captcha validation. Easy and simple to use.

Dev Defined CAPTCHA

•    ASPNET

This is an ASP.NET C# implementation of a CAPTCHA. You can choose any; size, font, color, background, pattern, add random lines or even add a background image. Also includes an audible version of the captcha text as well as refresh functionality.

Recaptcha for .NET

A library that allows a developer to easily integrate Google's Recaptcha service in an ASP.NET application.

django-simple-captcha - Django Simple Captcha is an extremely simple, yet highly customizable Django application to add captcha images to any Django form

•    Python

Django Simple Captcha is an extremely simple, yet highly customizable Django application to add captcha images to any Django form. The current development version supports Python3 via the six compatibility layer. You will need to install Pillow because PIL doesn't support Python3 yet.

captcha - Captcha for Laravel 5

•    PHP

A simple Laravel 5 service provider for including the Captcha for Laravel 5. The Captcha Service Provider can be installed via Composer by requiring the mews/captcha package and setting the minimum-stability to dev (required for Laravel 5) in your project's composer.json.

Java Security Image Generator / CAPTCHA

•    Java

SkewPassImage / CAPTCHA - A tiny java library (jar) which includes a servlet to display skewed security image (skewed pass code). Javadocs, example war, jar library - are all included. Ability to change and update the skewing mechanism using props file

The ASP CAPTCHA Project

•    VB

The ASP CAPTCHA Project (ASP Implementation of CAPTCHA) CAPTCHA is an acronym for quot;Completely Automated Public Turing Test to Tell Computers amp; Humans Apartquot;. It can generate amp; grade tests that: ? Most humans can pass ? Current computer programs can't

Silverlight Captcha

•    Silverlight

Simple Silverlight Captcha.

Distinct CAPTCHA Web Service

Distinct CAPTCHA used to add CAPTCHA to asp.net, InfoPath and SharePoint. The web service supports two methods one for generate and one to validate

Captcha - PHP Captcha library

•    PHP

PHP Captcha library