KeyCAPTCHA

<h4>Free Variants of Using WordPress CAPTCHA – KeyCAPTCHA</h4>
<ol>
<li>Anti-spam protection. Social advertising. Monetization through commercial ads.</li>
<li>Anti-spam protection. Monetization through commercial ads.</li>
<li>Anti-spam protection. Social advertising.</li>
<li>Anti-spam protection without any ads.</li>
</ol>
<h4>Social Features:</h4>
<p>You may support charity funds by enabling social advertising in our CAPTCHA.<br />
Also you can earn money by specifying social and commercial advertising shares in CAPTCHA on your website.</p>
<h4>KeyCAPTCHA Unique Technologies</h4>
<ul>
<li>Instead of guessing symbols, our WordPress CAPTCHA offers visitors to complete an easy interactive task.</li>
<li>If CAPTCHA hasn’t been solved correctly, page refreshing doesn’t take place that allows the user not to fill in the form repeatedly. It occurs since there is an initial checkup of CAPTCHAs in our CAPTCHA servers before sending a filled-in form to the protected web server.</li>
<li>Our CAPTCHA also can be used even if your hosting provider blocks all outgoing connections.</li>
</ul>
<h4>Effective Anti-Spam Protection</h4>
<ul>
<li>The geo-cluster is used to operate our CAPTCHA service. Our geo-cluster includes the servers located in diverse European data centers. Some servers are in the special DDoS stable data centers in Switzerland to ensure trouble-free 24x7x365 mode service operation.</li>
<li>Our CAPTCHA blocks spammers using anonymizers or anonymous HTPP proxies to distribute a hand spam.</li>
<li>There is no info of correct CAPTCHA solution in the visitor’s browser.</li>
<li>CAPTCHA verification is processed by the our CAPTCHA servers.</li>
<li>Data transferring between your web server, the visitor’s browser and our CAPTCHA servers is protected by a digital signature.</li>
<li>112 to 165 bit variable length password is used to generate a digital signature.</li>
<li>Our CAPTCHA is a code executable in the visitor’s browser. It is not a static image as used in typical CAPTCHAs.</li>
<li>Having received our CAPTCHA, it’s virtually impossible to transfer it to third parties in order to run any task what spammers also do bypassing typical CAPTCHAs.</li>
<li>Probability of guessing the answer by submitting a random solution is 1 to 30,000,000.</li>
<li>CAPTCHA-used images are transferred encryptedly.</li>
</ul>
<h4>Integration with WordPress</h4>
<p>Our CAPTCHA protects the following forms:</p>
<ul>
<li>Registration form</li>
<li>Comment form</li>
<li>Login form</li>
<li>Lost password form</li>
<li>Contact Form 7</li>
</ul>
<p>Compatibility and Features:</p>
<ul>
<li>Supports Trackbacks and Pingbacks</li>
<li>Our CAPTCHA is compatible with BuddyPress plugin</li>
<li>Our CAPTCHA supports two operating modes: Flash and HTML5. HTML5 CAPTCHA mode is used in most modern browsers, such as Mozilla FireFox, Google Chrome, Safari, and also used in iPhone and iPad. The Flash mode has been developed to be used in Internet Explorer and Opera. While loading, CAPTCHA identifies its operating mode depending on the visitor’s browser.</li>
</ul>
<h4>ATTENTION</h4>
<p>To install our WordPress CAPTCHA you should follow instructions in Installation tab. Otherwise the CAPTCHA won’t work correctly.</p>
<h4>KeyCAPTCHA Affiliate Program</h4>
<p>KeyCAPTCHA Affiliate Program allows publishers as well as any Internet user to collect incomes. For more information on The KeyCAPTCHA Affiliate Program, go to http://keycaptcha.wordpress.com/captcha-for-site-owners/affiliate-program/</p>
<h3>ATTENTION</h3>
<p>To install our CAPTCHA you have to follow instructions in Installation tab. Otherwise the CAPTCHA won’t work correctly.</p>
<h3>KeyCAPTCHA Translation</h3>
<ul>
<li>Our CAPTCHA is available in Armenian</li>
<li>Our CAPTCHA is available in Bulgarian</li>
<li>Our CAPTCHA is available in Chinese</li>
<li>Our CAPTCHA is available in Czech</li>
<li>Our CAPTCHA is available in Danish</li>
<li>Our CAPTCHA is available in Dutch</li>
<li>Our CAPTCHA is available in English</li>
<li>Our CAPTCHA is available in Estonian</li>
<li>Our CAPTCHA is available in French</li>
<li>Our CAPTCHA is available in German</li>
<li>Our CAPTCHA is available in Greek</li>
<li>Our CAPTCHA is available in Hebrew</li>
<li>Our CAPTCHA is available in Hungarian</li>
<li>Our CAPTCHA is available in Italian</li>
<li>Our CAPTCHA is available in Lithuanian</li>
<li>Our CAPTCHA is available in Norwegian</li>
<li>Our CAPTCHA is available in Portuguese</li>
<li>Our CAPTCHA is available in Polish</li>
<li>Our CAPTCHA is available in Romanian</li>
<li>Our CAPTCHA is available in Russian</li>
<li>Our CAPTCHA is available in Slovak</li>
<li>Our CAPTCHA is available in Spanish</li>
<li>Our CAPTCHA is available in Swedish</li>
</ul>


KeyCAPTCHA – Social WordPress CAPTCHA

See this otherview (rus): https://intsystem.org/captcha/vzlom-keycaptcha/



It is unsecure

Our captcha is the free unique anti-spam solution. This captcha does not require any text typing. Moreover, the captcha contains social features.

Takayuki Miyoshi

<p>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.</p>
<p>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.</p>
<h4>How does it work?</h4>
<p>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.</p>
<p>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.</p>
<p>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.</p>
<h4>How to use with your plugin</h4>
<p>Note: Below are instructions for plugin developers.</p>
<p>First, create an instance of ReallySimpleCaptcha class:</p>
<pre><code>$captcha_instance = new ReallySimpleCaptcha();
</code></pre>
<p>You can change the instance variables as you wish.</p>
<pre><code>// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array( 0, 0, 0 );
</code></pre>
<p>See really-simple-captcha.php if you are interested in other variables.</p>
<p>Generate a random word for CAPTCHA.</p>
<pre><code>$word = $captcha_instance->generate_random_word();
</code></pre>
<p>Generate an image file and a corresponding text file in the temporary directory.</p>
<pre><code>$prefix = wp_rand();
$captcha_instance->generate_image( $prefix, $word );
</code></pre>
<p>Then, show the image and get an answer from respondent.</p>
<p>Check the correctness of the answer.</p>
<pre><code>$correct = $captcha_instance->check( $prefix, $the_answer_from_respondent );
</code></pre>
<p>If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.</p>
<p>And last, remove the temporary image and text files, as they are no longer in use.</p>
<pre><code>$captcha_instance->remove( $prefix );
</code></pre>
<p>That’s all.</p>
<p>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>.</p>


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.

KeyCAPTCHA – Social WordPress CAPTCHA vs Really Simple CAPTCHA