Olly - OWMC

Many people use WP as a fully fledged CMS, building sites which don’t even have a blog. In such cases, the WP comments functionality is a waste of pixels and needs completely removing. Comment Crusher was made to quickly and thoroughly clear your install of every trace of comment functionality.
For many years I have used this collection of hooks to achieve this end. So came the idea to put it in a plugin and make it available to the masses. Simply activate this plugin and never worry about comments again.
When activated, even though all pre-existing comments on your site won’t be visible, they do still exist in your database. This plugin doesn’t delete them. And so deactivating the plugin will restore full comments functionality and reveal all previous comments again.
This plugin does not collect any data, neither does it modify your database.
<ul>
<li>Disable comment and trackback support from all post-types</li>
<li>Deactivate comments and pings on the front end</li>
<li>Hide all existing comments</li>
<li>Remove the comment metabox from the dashboard</li>
<li>Remove comments link from the toolbar</li>
<li>Remove the admin menu link for comments</li>
<li>Redirect anyone trying to access the comments admin page </li>
</ul>
This plugin was built using the <a href="https://wppb.me" rel="nofollow ugc">WP Plugin Boilerplate</a> and the custom functionality code I think goes back to <a href="https://gist.github.com/mattclements/10a997775894c7a0eba1" rel="nofollow ugc">Matt Clements in 2013</a>.

Comment Crusher

Disable and remove comments on your WP site.

Automattic

Donncha O Caoimh (a11n)

This plugin adds a stylesheet or image to your blog’s html source code. When a browser loads that stylesheet or image a cookie is dropped. If that user then leaves a comment the cookie is checked. If it doesn’t exist the comment is marked as spam. 
The plugin can also check how long it took a user to enter a comment. If it’s too fast it’s probably a spam bot. How fast can a legitimate user enter their name, email, web address and enter a well thought out comment?
For the adventurous, add these lines to your .htaccess and it will block spam attempts before they ever get to WordPress. Replace the Xs with the cookie that was set in your browser after viewing your blog. You can also find the cookie value by examining the page source code and looking for “css.php?k=XXXXXXXXXXXXXXXXXXX”. Make sure the lines go above the standard WordPress rules.
<pre><code> RewriteCond %{HTTP_COOKIE} !^.*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.*$
 RewriteRule ^wp-comments-post.php - [F,L]
</code></pre>
If you use WordPress MU, replace wp-comments-post.php above with wp-signup.php to block spam signups.
<pre><code> RewriteCond %{HTTP_COOKIE} !^.*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.*$
 RewriteRule ^wp-signup.php - [F,L]
</code></pre>

Cookies for Comments

If you don't use any other spam filter plugins, then you can rely on this to stop spam comments for sure!

Must have, if you don't use any other spam filters!

I'd been getting a dozen spams a day on two of my sites. We installed "Stop Spam Comments" on one and "Cookies for Comments" on the other. Both worked perfectly. No more spam. Thanks!



very easy and no more spam!

Sets a cookie on a random URL that is then checked when a comment is posted. If the cookie is missing the comment is marked as spam.

Comment Crusher vs Cookies for Comments