Crucial Innovations

Comment Links New Tab will allow you to have your comment author name links open in a new tab or window. In other words, instead of leaving your site completely when clicked, they will open in a new tab.
This will increase the likelihood that visitors will continue browsing your website.
Simple, fast, and effective!
<h4>Some of the features include:</h4>
<ul>
<li>Whitelist your domain</li>
<li>Select a css class, id, or custom value</li>
<li>Enter a css value</li>
<li>Open comment links in a new tab or the same tab</li>
<li>Select keep original, external nofollow, nofollow, or dofollow rel (relationship) link attribute</li>
<li>Use an optional title</li>
<li>Option to Compress/Minify Js (javascript file)</li>
<li>Works with http:// and https:// links</li>
</ul>

Comment Links New Tab

Stop sending visitors away - open comment author links in a new tab or window with: Comment Links New Tab.

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.

Comment Links New Tab vs Affiliatize Me