webaction

<p><strong>Show External Links</strong> provides information on all external links on the site pages.<br />
You can see the info window with the total number of links on the current page. Also, all links stand out and become visible.<br />
If you do not see all the links on the page, check the source code. Perhaps, they are hidden.</p>
<blockquote>
<p>The plugin works only for authorized users with administrative rights.<br />
  The plugin does not take into account the WordPress admin bar and the links specified in the skip-sites field.</p>
</blockquote>
<p><a href="https://web-svb.github.io/sel.github.io" rel="nofollow ugc">Follow plugin development on Github.</a></p>
<h4>Features</h4>
<ul>
<li>Information on the number of external links on the page</li>
<li>Highlight external links for easy visual detection</li>
<li>Exclude certain sites from checking</li>
</ul>
<h4>Bundled Translations</h4>
<ul>
<li>English</li>
<li>Russian</li>
</ul>


Show External Links

With the plugin Show External Links easy to find all the external links on the pages of the site.

jmarreros

<p>This Plugin allows to use an external image as Featured Image, this can be especially useful if you house your images in another location.</p>
<p>This Plugin is compatible with Nelio External Featured Image Metadata, so you can reuse your data in case you want to uninstall Nelio Plugin.</p>


External URL Featured Image

It is what I was looking for: simplicity.

$external_image = get_post_meta( $post->ID, '_dcms_eufi_img', true );

Works well for me

Use an external url image as Featured Image for your posts, pages, and other kind of post types.

Show External Links vs External URL Featured Image