tex0gen

This WordPress plugin ensures that search engine indexing is automatically turned OFF if the site’s URL doesn’t match the provided live site URL. It’s especially useful for development and staging environments, where you might not want content to be indexed by search engines.
Features: 
– Automatically turns off search engine indexing for non-live sites. 
– Provides an admin settings page to specify the live site URL. 
– Displays an admin notice if indexing has been turned off due to URL mismatch. 
– Encodes the live site URL to prevent inadvertent changes when using migration tools. 
– Admin notice prompts for setting the live site URL if it hasn’t been configured yet.
<h3>Usage</h3>
<ol>
<li>After activating the plugin, go to the admin dashboard.</li>
<li>Navigate to <code>Settings</code> -> <code>Prevent Indexing</code>.</li>
<li>Enter your live site URL in the provided input field and save.</li>
<li>If the current site’s URL doesn’t match the provided live site URL, search engine indexing will be turned off, and an admin notice will inform you of the same.</li>
</ol>
<h3>License</h3>
<a href="https://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">GPLv2 or later</a>

Prevent Indexing on Non-Live Sites

Prevent your WordPress website from being indexed by search engines when it's not on the live site.

sdesalas

This plugin allows WordPress to block over 95% of spam comments using a time-based hash.
This allows for a minimum sanity check and yet should remove almost all spam comments 
without the need to sign up to any third party APIs.
The plugin has been tested in real world conditions for around 12 months. It will not block 
real comments and it is pretty effective against spam, however it only uses a very simple 
algorithm and for that reason some spam comments may still make it through.

WP Simple SpamCheck

This plugin allows WordPress to block over 95% of spam comments using a time-based hash.

Prevent Indexing on Non-Live Sites vs WP Simple SpamCheck