cobianzo

This is a very simple plugin that allows you to associate a tooltip to any link in the block editor. 
Open the link options, click on the pencil icon to edit it, then make sure that the Advanced panel 
is open, and find the new input box for the tooltip. 
You will see the tooltip when you hover with the mouse the link in the frontend.
Main features: 
– new ‘tooltip’ input box in the CMS editor ‘edit link’, under ‘Advanced’ tab. 
– showing this new field as a simple CSS-only tooltip in the frontend 
– CSS rules use some variables to easily modify the aspect of the tooltip.

GB CSS Tooltip

Simple functionality that includes an extra option when editing a link within the block editor: nice CSS tooltips.

sojournings

Hints enables you to provide a better UX with respect to links/topics. Some keywords/words, need more explanation or/and external resources to be explained further, if the user needs to know more. Normally, you would achieve this by creating a link/anchor to that resource. Hints, makes it possible for your users to get additional information, about a topic/resource, without leaving your post. Too many links in a post, do spoil the broth.
Features:
<ul>
<li>Small, Simple to use and install, lightweight.</li>
<li>Uses jQuery, since WP comes bundled with it.</li>
<li>No settings, no nothing. Just install and start using it.</li>
<li>Shortcodes based.</li>
<li>Two options to set within shortcodes. See the tutorial video below.</li>
</ul>
Tutorial Video:
<a href="https://sojourner.co/blog/code/wp-plugin-hints.html" rel="nofollow ugc">Here’s the usage & tutorial video</a>.
For Support and Feature Requests:
Use the comment box over at <a href="https://sojourner.co/blog/code/wp-plugin-hints.html" rel="nofollow ugc">https://sojourner.co/blog/code/wp-plugin-hints.html</a>
<h3>Usage</h3>
<h3>Use shortcodes within posts, as shown below.</h3>
<pre><code>[hints unique_id="hints"] A shortcode is a WordPress specific code, that lets you do all kinds of nauthy things. More about WordPress' shortcodes. [/hints]

[hints unique_id="options" custom_text="info about options"] 'unique_id' identifies each infocard or hint uniquely. As the option name suggests, the id has to be unique. If not supplied, one is generated auto-magically for you. The other option is 'custom_text'. If this option is set, the default plus icon is not used. This option is only for convenience. Using this option, may prove to be redundant.[/hints]
</code></pre>

Hints

Provide a better user experience for you users, when they read your posts. Reduce the number outgoing, non-essential links.

GB CSS Tooltip vs Hints