Erick Hitter

Oomph, Inc.

Allows users to point WordPress objects (posts, pages, custom post types) to a URL of their choosing, which is particularly useful for injecting non-WordPress content into loops. The object appears normally in any loop output, but visitors to the object will be redirected to the specified URL. The plugin also allows you to choose the type of redirect, either temporary (302), or permanent (301).
Through a filter, the External Permalinks Redux meta box can easily be added to custom post types. There is also a function available for use with WordPress’ <code>add_meta_box</code> function.
This plugin was originally written for use on WordPress.com VIP. It is inspired by and backwards-compatible with Mark Jaquith’s Page Links To plugin, meaning users can switch between plugins without risk of losing any existing external links.
This plugin is translation-ready.

External Permalinks Redux

Allows you to point WordPress objects (posts, pages, custom post types) to a URL of your choosing.

Curtis V. Schleich

Some industries’ compliance recommendations suggest that a notice be presented anytime someone leaves your site. I searched for a plugin to do this, and came up empty, so here you go!
Features: 
* Works with little or no configuration. 
* The title and the body of the exit box, and the text on the buttons are all editable, and honor shortcodes. 
* There are also options for providing a visual indication on your selected links, and for opening selected links in a new window/tab. 
* You can completely customize the display of the dialog by modifying the CSS. 
* You can set a timeout that will continue or cancel when the time expires, with optional visual feedback. 
* Add CSS classes to selected links. 
* Add Custom CSS that applies to the whole site. 
* You can add custom tags in the anchor tag for each link to provide custom title and body for each link. 
* Compatible with simple forms in some cases. Should work well with WooCommerce External/Affiliate product pages. 
* Will honor <a target=”whatever”> for selectively opening in a new tab/window. 
* Allows you to add rel=”nofollow” to all outbound links. 
* You can now exclude individual links by applying a CSS class. 
* Accessibility issues addressed with library updates.
<h3>NOTICE</h3>
When upgrading, please be sure to clear the cache if you’re using a caching plugin like the excellent WP Fastest Cache (http://www.wpfastestcache.com/) or something similar. There have been substantial changes and having older versions of the files cached will almost certainly lead to problems when an external link is clicked.
<h3>Credit where credit is due</h3>
I have made liberal use of the excellent WordPress Plugin Template by Hugh Lashbrooke found at https://github.com/hlashbrooke/WordPress-Plugin-Template. Thanks, Hugh!
Also, to <a href="https://htmlguy.com" rel="nofollow ugc">HTMLGuy</a>, the maker of <a href="https://htmlguyllc.github.io/jAlert/" rel="nofollow ugc">jAlert</a>, a very versatile and simple alert component! Thanks!

Exit Notifier

Provides a way to display a notification to site users that they have clicked an external link and are leaving your site.

External Permalinks Redux vs Exit Notifier