# Developer's Guide

**Important** : Version 1.0 of the reCAPTCHA API is no longer supported, please upgrade to Version 2.0. [Learn more](https://developers.google.com/recaptcha/docs/faq)

Welcome to the developer documentation for reCAPTCHA! reCAPTCHA lets you embed a
[CAPTCHA](http://captcha.net/) in your web pages in order to protect them against spam
and other types of automated abuse. Here, we explain how to add reCAPTCHA to your page.

## Audience

This documentation is designed for people familiar with HTML forms and server-side processing.
To install reCAPTCHA, you will probably need to edit some code.

We hope you find this documentation easy to follow. Make sure to join the
[reCAPTCHA developer forum](http://groups.google.com/group/recaptcha) to give
feedback and discuss the API.

## Overview

### API Keys

To use reCAPTCHA, you need to
[sign up for API keys](http://www.google.com/recaptcha/admin#whyrecaptcha)
for your site. The keys are unique to the domain or domains you specify, and
their respective sub-domains. Specifying more than one domain could come in handy
in the case that you serve your website from multiple top level domains (for
example: yoursite.com, yoursite.net).

By default, all keys work on "localhost" (or "127.0.0.1"), so you can always
develop and test on your local machine.

### Integration

Once you've signed up for API keys, you can add reCAPTCHA to your site and [customize](https://developers.google.com/recaptcha/old/docs/customization) the widget. If you're using one of the following programming environments or applications, click on the link below for further instructions.

### Programming Environments:

- [PHP](https://developers.google.com/recaptcha/old/docs/php)
- [ASP.NET](https://developers.google.com/recaptcha/old/docs/aspnet)
- [Classic ASP](https://developers.google.com/recaptcha/old/docs/asp) (contributed by Mark Short)
- [Java/JSP](https://developers.google.com/recaptcha/old/docs/java)
- [Perl](https://developers.google.com/recaptcha/old/docs/perl)
- [Python](http://python.org/pypi/recaptcha-client)
- [Ruby](http://bitbucket.org/mml/ruby-recaptcha/wiki/Home) (contributed by McClain Looney)
- Another [Ruby](http://github.com/ambethia/recaptcha/) library from Jason L Perry
- [Ruby/Rack](http://github.com/achiu/rack-recaptcha) (contributed by Arthur Chiu)
- [JSP Mailhide Tag](http://code.google.com/p/mailhide-tag/) (contributed by Tamas Magyar)
- [ColdFusion](http://recaptcha.riaforge.org/) (contributed by Robin Hilliard)
- [WebDNA](http://www.danstrong.com/reCAPTCHA-WebDNA.html) (contributed by Dan Strong)

### Applications:

- [MediaWiki](https://developers.google.com/recaptcha/old/docs/mediawiki)
- [phpBB](https://developers.google.com/recaptcha/old/docs/phpbb)
- [FormMail](https://developers.google.com/recaptcha/old/docs/formmail)
- [Movable Type](http://multipart-mixed.com/software/recaptcha.html) (contributed by Josh Carter)
- [Drupal](http://drupal.org/project/recaptcha) (contributed by Rob Loach)
- [Symfony](http://trac.symfony-project.com/trac/wiki/sfReCaptchaPlugin) (contributed by Arthur Koziel)
- [TYPO3](http://typo3.org/extensions/repository/view/jm_recaptcha/current/) (maintained by Markus Blaschke, contributed by Jens Mittag. See also the [example](http://typo3.org/extensions/repository/view/jm_recaptcha_example/current/) of using the plugin)
- [NucleusCMS](http://lordmatt.co.uk/item/812/) (contributed by Matt)
- [vBulletin](http://www.vbulletin.org/forum/showthread.php?t=151824) (contributed by Magnus)
- [Joomla](http://code.google.com/p/joomla-recaptcha/) (contributed by Mark Fabrizio)
- [Joomla Community Builder](http://code.google.com/p/cb-recaptcha/) (contributed by Ayan Debnath)
- [JSP Mailhide](http://code.google.com/p/mailhide-tag/) (contributed by Tamas Magyar)
- [bbPress](http://www.gospelrhys.co.uk/plugins/bbpress-plugins/recaptcha-bbpress-plugin) (contributed by Rhys Wynne)
- [ExpressionEngine](http://code.google.com/p/expressionengine-recaptcha/) (contributed by Jaspaul Aggarwal)
- [FlatPress](http://www.ramblingross.co.uk/2010/08/11/recaptcha-for-flatpress/) (contributed by Ross Fruen)
- [PHPKIT](http://www.blutrausch-gilde.com/contents/download/ReCAPTCHA) (contributed by Norman Huth)