DjZoNe

More than that, it checks if all fields filled correctly, and also makes sure to avoid comment duplication, and has flood protection capabilities as well.
Probably one of the best ways you could spice up your WordPress Blog with AJAX; readers love it! Must see for yourself.
This plugin works well in all major Web browsers, and uses discrete AJAX. 
That means if JavaScript disabled, it’s using the original comment posting method.
Ajax Comments known to work well, with Authimage plugin, but I rather suggest Akismet, as it is free for personal use.
Features:
<pre><code>* comment form validation happens server-side without refreshing or leaving the page
* Script.aculo.us Fade In/Out Effects make readers happy
* works with AuthImage captcha word verification plug-in to prevent comment spam
* still works traditionally if browsers don't support JavaScript (or have it disabled)
* uses existing theme code to match styled comment threads when producing new comments
* 25-second server timeout ensures readers aren't left hanging
* works in current versions of Firefox, Internet Explorer, Opera, Netscape, and Safari.
</code></pre>
Recommendations:
<pre><code>* perfectly compliments any well-styled comment form design-don't design without it
* best when moderation is off (seems more real-time) and AuthImage is installed (self-moderation is the best moderation)
</code></pre>
<h3>Known bug</h3>
I’ve discovered that AJAX Comments 2.0 stops working properly if you 
have ShowOnFrontPage plugin (v0.3.1) installed.
And we got another report, that it also stops, when you have SpamKarma activated.
We are working on a solution.
<h3>AuthImage Integration</h3>
<ol>
<li>Open ajax-comments.php and uncomment lines: 92, 152, 153.</li>
<li>
Open comments.php from your /themes directory and use the following code (mostly just the ids) for AuthImage to appear in your comments form:
<pre><code> <?php if ( !$user_ID ) : ?>

 <img id="auth-image" src="<?php echo get_option('siteurl'); ?>/wp-content/plugins/authimage/authimage-inc/image.veriword.php" alt="Verification Image" />
 <label for="code">Word Verification (<a href="#" onclick="document.getElementById('auth-image').src+='?'+Math.random();return false" title="Generate another Captcha Word Verification image.">can't read it? try another!</a>)</label>
 Please type the letters you see in the picture.
 <input name="code" id="code" type="text" class="text" tabindex="5" />

 <?php endif; ?>
</code></pre>
</li>
</ol>

AJAX Comments

Post comments quickly without leaving or refreshing the page.

Alessandro Lin

Captcha works fine with website cache. 
Adds Captcha Asynchronously anti-spam methods to WordPress. Include login form, registration form, lost passwordform and comments form. The asynchronously method allows captcha to work well when a page cache, server cache or plugin cache, is active.
<h3>Demo</h3>
<a href="https://captcha-ajax.eu" rel="nofollow ugc">View:</a>
<h3>Features</h3>
<ul>
<li>Captcha for login form</li>
<li>Captcha for login form obtained with the function wp_login_form(). Login form embedded in a page.</li>
<li>Captcha for registration form</li>
<li>Captcha for lost password form.</li>
<li>
Captcha for comments form
</li>
<li>
Captcha for Contact Form 7
</li>
<li>Captcha for WPForms</li>
<li>
Captcha for Forminators form.
</li>
<li>
Captcha for WooCommerce plugin. Login form, Lost Password form.
</li>
<li>
Select the letters type from the options – Capital letters, Small letters or Captial & Small letters.
</li>
<li>Select the captcha type from the options – Alphanumeric, Alphabets or numbers.</li>
<li>
Select the captcha image. Default image or Black and white or Multicolor or Icons ( 27 icons available from fontawesome.com ) or Arithmetics. See images in screenshots.
</li>
<li>
Firewall. Limit rate of failed login attempts for each IP.
</li>
<li>
REST API
</li>
</ul>
Firewall details: 
Limit failed login attempts. 
Temporary blocks an Internet address from making further attempts after a specified limit on failed retries is reached. 
Option active for login form, login form embedded, registration form, lost password form. Select the feature in the dashboard.
REST API details: 
– The following address, reachable with a browser: 
” https://your_site/wp-json/captcha-ajax/v1/transients_expired ” 
will cause the cleaning of expired transients. 
Performs this task no more than once every 2 hours, further requests will be ignored.
<ul>
<li>
If your web site has a caching plugin installed or uses server-side caching, it is best to exclude the page from caching: 
” https://your_site/wp-json/captcha-ajax/v1/transients_expired “
</li>
<li>
REST API Filter for Exposing Menus Publicly in WordPress. Optional.
</li>
</ul>
Captcha for Contact Form 7 details: 
1. Install and activate CF7 and Captcha Ajax. 
2. Go to Captcha Ajax settings. CF7 yes and save. 
3. Create your contact form with CF7. 
4. Edit your new CF7 contact form: 
 Click on the line before [submit “Submit”]. This positions the cursor. 
 Click on the Captcha Ajax Tag. 
 Click on Insert Tag. This inserts the shortcode of Captcha Ajax. 
 Click on Save. 
5. Add the CF7 shortcode to the page, post or text widget and save. 
6. Cache. Purge if it is active. 
Done
Captcha for WPForms details: 
1. Install and activate WPForms and Captcha Ajax. 
2. Go to Captcha Ajax settings. WPF yes and save. 
3. Create your contact form with WPForms. 
4. Add the WPForms shortcode to the page, post or text widget and save. 
5. Cache. Purge if it is active. 
Done
Captcha for Forminator form details: 
1. Install and activate Forminator form and Captcha Ajax. 
2. Go to Captcha Ajax settings. Forminator yes and save. 
3. Create your contact form with Forminator. 
4. Add the Forminator shortcode to the page, post or text widget and save. 
5. Cache. Purge if it is active. 
Done
Captcha for WooCommerce details: 
This feature is synchronized with the WordPress Login. 
If captcha for WordPress Login is enabled, captcha for WooCommerce Login module is also enabled.
<h3>Support</h3>
Thanks for downloading and installing my plugin. You can show your appreciation and support future development by donating. https://www.paypal.me/a6419

Captcha Ajax

amazing

Captcha, ajax and site cache. For logins, for contact forms, for WooCommerce. Include Firewall and REST API.

AJAX Comments vs Captcha Ajax