aomm

火柴手写码，是将海量手写图片资源进行碎片化处理，随机组合、加密而成；由于源数据重复概率低、手写文字差异大（即使同一个人多次书写同一数字，? ?结果也不尽相同）、手写字符书写不规则等特点，使得现有OCR技术很难识别；同时我们结合大数据处理和云计算技术，为开发? 提供? 晰、安? ?、方便的云验证码服务。

火柴手写码

火柴手写码，是基于海量手写字符、复杂安全技术而生成的图片验证码，提高了破解难度。火柴手写码，由火柴棍工作室研发，其开放平台已为开发者提供清晰、安全、方便的云验证码服务。

Silkalns

WP Chill

Cristian Raiber

A very useful plugin for everyone using WordPress. Adds reCaptcha security to the WordPress login form, register form and comment form. This plugin could help your blog get rid of a lot of spam comments or brute-force attacks.
Nothing gets passed it if the reCaptcha doesn’t validate.
A few notes about the plugin:
<ul>
<li>Supports audio or image captcha types</li>
<li>Can generate the reCaptcha image / audio type in a number of predefined languages</li>
<li>Adds reCaptcha protection to the WordPress login form</li>
<li>Adds reCaptcha protection to the WordPress register form</li>
<li>Adds reCaptcha protection to the WordPress comment form</li>
<li>Adds reCaptcha protection to the WordPress recover password form</li>
</ul>

Uber reCaptcha

This plugin adds the reCaptcha form to the WordPress login form, recover password form, register form and comment form.

火柴手写码 vs Uber reCaptcha