WebTechee

Smart External Links Manager detects external links in post content and adds:
<ul>
<li>target=”_blank”</li>
<li>rel=”noopener noreferrer”</li>
</ul>
Internal links, anchor links, mailto, and tel links are ignored. 
This plugin is intentionally lightweight and works out of the box without configuration.

Webtechee External Links Security

Automatically adds secure attributes to external links in post content.

Janine

This plugin adds and removes link relations such as nofollow and noreferrer to your external links. Furthermore, indication of external links by adding a custom icon to the link text. This plugin also adds automatically that external links will be opened in a new tab.
<ul>
<li>Add rel=nofollow for all the external links of your posts / pages / menus</li>
<li>Add target=_blank for all the external links of your posts / pages / menus</li>
<li>Exclude domains from addding rel=nofollow for the selected external links</li>
<li>Remove rel=noreferrer for all the external links of your posts / pages</li>
<li>Activate custom icon to indicate external links</li>
<li>Choose from different icons to mark links</li>
<li>Superscript Icon or regular size</li>
<li>Add custom CSS class to icon</li>
</ul>
The plugin is written by Janine, and is based on CyberNetikz Nofollow for external links plugin.

Customize External Links and add Icon

Customize link attributes, such as nofollow links, remove noreferrer, add icons to indicate external links

Webtechee External Links Security vs Customize External Links and add Icon