Cristi Tamas

Cristian Outbound Manager is a lightweight and reliable plugin that automatically handles all outbound/external links on your WordPress site. Improve SEO, security and user experience with zero effort.
Once activated, the plugin scans your post content and applies the attributes you choose:
<ul>
<li>Open external links in a new tab (<code>target="_blank"</code>)</li>
<li>Add <code>rel="nofollow"</code></li>
<li>Add <code>rel="noopener noreferrer"</code> for security</li>
<li>Exclude specific domains from being modified</li>
</ul>
Perfect for blogs, business sites, affiliate sites, WooCommerce stores and any website that uses outbound links.
This plugin is fully compatible with PHP 7.4 – 8.4.
<h3>Features</h3>
<ul>
<li>Automatically detect outbound/external links</li>
<li>Add <code>target="_blank"</code> to open links in a new tab</li>
<li>Add <code>rel="nofollow"</code> to external links</li>
<li>Add <code>rel="noopener noreferrer"</code> for security</li>
<li>Exclude domains (one per line)</li>
<li>Lightweight and fast — no impact on performance</li>
<li>Works with Gutenberg, Classic Editor, page builders and custom post types</li>
</ul>

Cristian Outbound Manager

Manage outbound links automatically: open in new tab, add nofollow, noopener, and exclude domains.

Erin McIntyre

This plugin searches links on your site for the domain that you specify in the settings, adds your affiliate ID, and makes those links open in a new tab when clicked.
The plugin produces XHTML Strict compliant code and is search engine optimized (SEO). 
This is done using JavaScript’s <code>window.open()</code>-function. It adds only a few lines of vanilla JavaScript to the page, and does not require any external libraries like jQuery.
Most other plugins perform a hack by altering the <code>target</code> parameter (i.e. <code><a href="http://somewhere.example" target="_blank"></code>). That method is not XHTML Strict compliant.
This plugin handles the links client-side, which lets search engines follow the links properly. Also, if a browser does not support JavaScript, the plugin is simply inactive, and does not result in any errors.
Credits 
Inspired by the <a href="https://wordpress.org/plugins/open-external-links-in-a-new-window/" rel="ugc">External Links in New Window / New Tab</a> plugin.
Known bugs 
The plugin conflicts with other plugins that change the links’ `onClick´ attribute.

Cristian Outbound Manager vs Affiliatize Me