Takayuki Miyoshi

Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for <a href="https://contactform7.com/" rel="nofollow ugc">Contact Form 7</a>, however, you can use it with your own plugin.
Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions.
<h4>How does it work?</h4>
Really Simple CAPTCHA does not use PHP “Sessions” for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts.
When you generate a CAPTCHA, Really Simple CAPTCHA creates two files for it; one is an image file of CAPTCHA, and the other is a text file which stores the correct answer to the CAPTCHA.
The two files have the same (random) prefix in their file names, for example, “a7hk3ux8p.png” and “a7hk3ux8p.txt.” In this case, for example, when the respondent answers “K5GF” as an answer to the “a7hk3ux8p.png” image, then Really Simple CAPTCHA calculates hash of “K5GF” and tests it against the hash stored in the “a7hk3ux8p.txt” file. If the two match, the answer is confirmed as correct.
<h4>How to use with your plugin</h4>
Note: Below are instructions for plugin developers.
First, create an instance of ReallySimpleCaptcha class:
<pre><code>$captcha_instance = new ReallySimpleCaptcha();
</code></pre>
You can change the instance variables as you wish.
<pre><code>// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array( 0, 0, 0 );
</code></pre>
See really-simple-captcha.php if you are interested in other variables.
Generate a random word for CAPTCHA.
<pre><code>$word = $captcha_instance->generate_random_word();
</code></pre>
Generate an image file and a corresponding text file in the temporary directory.
<pre><code>$prefix = wp_rand();
$captcha_instance->generate_image( $prefix, $word );
</code></pre>
Then, show the image and get an answer from respondent.
Check the correctness of the answer.
<pre><code>$correct = $captcha_instance->check( $prefix, $the_answer_from_respondent );
</code></pre>
If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.
And last, remove the temporary image and text files, as they are no longer in use.
<pre><code>$captcha_instance->remove( $prefix );
</code></pre>
That’s all.
If you wish to see a live sample of this, you can try <a href="https://contactform7.com/captcha/" rel="nofollow ugc">Contact Form 7</a>.

Really Simple CAPTCHA

Needed this for an installation with custom forms. I used the plugin developers instructions and was able to make a fully custom implementation based on server side validation within 30 minutes. No more spam bots misusing the forms. Thank you!

Great work - easy to implement

Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.

MihChe

WPBruiser (formerly GoodBye Captcha) is an anti-spam and security plugin based on algorithms that identify spam bots without any annoying and hard to read captcha images.
WPBruiser completely eliminates spam-bot signups, spam comments, even brute force attacks, the second you install it on your WordPress website. It is completely invisible to the end-user – no need to ever fill out a Captcha or other “human-detection” field ever again – and it just works!
Unlike other anti-spam plugins, which detect spam comments and signups after the fact and move them to your spam folder, which you then have to delete – using up not only your website’s resources, but your time as well, WPBruiser prevents the bots from leaving spam in the first place. The result is that your site is not only spam free, it’s faster and more secure.
In addition, WPBruiser is completely self-contained and does not need to connect to any outside service. Your logins remain yours, 100%.
WPBruiser fights Brute Force attacks and eliminates spam-bots on comments, signup pages as well as login and password reset pages. At the click of a button, you can decide which forms to protect.
<h4>Summary of WPBruiser features</h4>
<ul>
<li>Standard WordPress Login form integration</li>
<li>Standard WordPress Register form integration</li>
<li>Standard WordPress Forgot Password form integration</li>
<li>Standard WordPress Comments form integration</li>
<li>Ability to set the maximum number of characters for each comment field</li>
<li>Logging with the ability to enable/disable it</li>
<li>Automatically Block IP Addresses</li>
<li>Automatically purge logs older than a certain number of days</li>
<li>Manually white-list trusted IP Address (IPV4 and IPV6)</li>
<li>Manually block/unblock IP Addresses (IPV4 and IPV6)</li>
<li>Properly detects client IP Address when using CloudFlare, Incapsula, Cloudfront, RackSpace, Sucuri CloudProxy, AWS ELB</li>
<li>Provides statistics, reports, maps and charts with all blocked spam attempts</li>
<li>No requests to external APIs</li>
<li>Can be switched to “Test Mode” – for testing</li>
<li>Compatible with WordPress Multisite – network admin interface ready</li>
<li>Compatible with cache plugins (WP Super Cache, W3 Total Cache, ZenCache, WP Fastest Cache and others)</li>
<li>Invisible for end users (works in the background)</li>
<li>Does not affect page loading times</li>
</ul>
<h4>Brute Force Protection</h4>
<ul>
<li>Automatically detects Brute Force attacks</li>
<li>Ability to automatically block IP Addresses</li>
<li>Prevents User Enumeration</li>
<li>Ability to block most dangerous IP addresses involved in brute force attacks</li>
<li>Ability to block most dangerous Anonymous Proxy IP addresses including TOR Networks, TOR Nodes and TOR Exit Points</li>
<li>Ability to Completely Disable XML-RPC service – it seamlessly works with Jetpack plugin activated</li>
<li>Ability to Disable XML-RPC Pingbacks</li>
<li>Email notifications when a Brute Force Attack is detected</li>
</ul>
<blockquote>
<h4>WPBruiser Available Extensions</h4>
WPBruiser is integrated with the most popular plugins
<dl>
<dt>Contact Forms Extensions</dt>
<dd>
<ul>
<li><a href="http://www.wpbruiser.com/downloads/contact-form-7/" rel="nofollow ugc">WPBruiser – Contact Form 7</a></li>
<li><a href="http://www.wpbruiser.com/downloads/gravity-forms/" rel="nofollow ugc">WPBruiser – Gravity Forms</a></li>
<li><a href="http://www.wpbruiser.com/downloads/ninja-forms/" rel="nofollow ugc">WPBruiser – Ninja Forms</a></li>
<li><a href="http://www.wpbruiser.com/downloads/formidable-forms/" rel="nofollow ugc">WPBruiser – Formidable Forms</a></li>
<li><a href="http://www.wpbruiser.com/downloads/fast-secure-contact-form/" rel="nofollow ugc">WPBruiser – Fast Secure Contact Form</a></li>
<li><a href="" rel="nofollow ugc">WPBruiser – Jetpack Contact Form (FREE – merged into the core)</a></li>
</ul>
</dd>
</dl>
<dl>
<dt>Membership Extensions</dt>
<dd>
<ul>
<li><a href="http://www.wpbruiser.com/downloads/buddypress/" rel="nofollow ugc">WPBruiser – BuddyPress</a></li>
<li><a href="http://www.wpbruiser.com/downloads/memberpress/" rel="nofollow ugc">WPBruiser – MemberPress</a></li>
<li><a href="http://www.wpbruiser.com/downloads/userpro/" rel="nofollow ugc">WPBruiser – UserPro</a></li>
<li><a href="http://www.wpbruiser.com/downloads/upme/" rel="nofollow ugc">WPBruiser – User Profiles Made Easy</a></li>
<li><a href="" rel="nofollow ugc">WPBruiser – Ultimate Member (FREE – merged into the core)</a></li>
</ul>
</dd>
</dl>
<dl>
<dt>eCommerce Extensions</dt>
<dd>
<ul>
<li><a href="http://www.wpbruiser.com/downloads/woocommerce/" rel="nofollow ugc">WPBruiser – WooCommerce</a></li>
<li><a href="http://www.wpbruiser.com/downloads/easy-digital-downloads/" rel="nofollow ugc">WPBruiser – Easy Digital Downloads</a></li>
<li><a href="http://www.wpbruiser.com/downloads/affiliatewp/" rel="nofollow ugc">WPBruiser – AffiliateWP</a></li>
</ul>
</dd>
</dl>
<dl>
<dt>Email Subscriptions Extensions</dt>
<dd>
<ul>
<li><a href="http://www.wpbruiser.com/downloads/mailpoet/" rel="nofollow ugc">WPBruiser – MailPoet</a></li>
<li><a href="http://www.wpbruiser.com/downloads/easy-forms-for-mailchimp/" rel="nofollow ugc">WPBruiser – Easy Forms for MailChimp</a></li>
</ul>
</dd>
</dl>
<a href="http://www.wpbruiser.com/extensions/" title="WPBruiser Extensions" rel="nofollow ugc">View all WPBruiser Extensions</a>
</blockquote>
WPBruiser is also integrated with the following plugins:
<ul>
<li>
Postmatic (https://wordpress.org/plugins/postmatic) 
WPBruiser offers protection for the entire email commenting system
</li>
<li>
Epoch (https://wordpress.org/plugins/epoch) 
WPBruiser offers protection for the entire chat and commenting system
</li>
<li>
wpDiscuz (https://wordpress.org/plugins/wpdiscuz/) 
WPBruiser offers protection for the entire commenting system
</li>
<li>
MailChimp for WordPress (https://wordpress.org/plugins/mailchimp-for-wp) 
WPBruiser offers protection for all forms the user will create with MailChimp
</li>
<li>
Ultimate Member (https://wordpress.org/plugins/ultimate-member) 
WPBruiser offers protection for Login, Registration and Reset Password forms
</li>
<li>
Jetpack by WordPress (https://wordpress.org/plugins/jetpack) 
WPBruiser offers protection for JetPack Contact Form
</li>
<li>
ZM Ajax Login & Register (https://wordpress.org/plugins/zm-ajax-login-register) 
WPBruiser offers protection for Login and Registration forms
</li>
<li>
Login With Ajax (https://wordpress.org/plugins/login-with-ajax) 
WPBruiser offers protection for Login, Registration and Lost Password forms
</li>
<li>
WP User Control (https://wordpress.org/plugins/wp-user-control) 
WPBruiser offers protection for Login, Registration and Lost Password forms
</li>
<li>
PlanSo Forms (https://wordpress.org/plugins/planso-forms/) 
WPBruiser offers protection for all forms
</li>
<li>
Theme My Login (https://wordpress.org/plugins/theme-my-login) 
WPBruiser offers protection for Login, Registration and Lost Password forms
</li>
<li>
Seamless Donations (https://wordpress.org/plugins/seamless-donations) 
WPBruiser offers protection for the donation form
</li>
</ul>
<h4>Technical support</h4>
If you notice any problems by using this plugin, please notify us and we will investigate and fix the issues. Ideally your request should contain: URL of the website (if your site is public), Php version, WordPress version and all the steps in order to replicate the issue (if you are able to reproduce it somehow)
<h4>Donate</h4>
If you find this plugin useful, please consider making a small <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=XVC3TSGEJQP2U" rel="nofollow ugc">donation</a>. Thank you

WPBruiser {no- Captcha anti-Spam}

An extremely powerful antispam plugin that blocks spam-bots without annoying captcha images.

Really Simple CAPTCHA vs WPBruiser {no- Captcha anti-Spam}