Corrado Franco

This plugin allows one to create footnotes by using markdown notation. 
It is for footnotes only. No other markdown tag is taken into account
Example:
<pre><code>I have more [^1] to say up here.

[^1]: To say down here.
</code></pre>
If used with jetpack and enabled markdown, it only shows the buttons without modifying the text content. 
Unlike jetpack-markdown, footnotes will appear in the exact point where they have been inserted. To go back to text mode click on the footnote number.
N.B 
This plugin also works with Gutenberg. But the button only appears in the Classic Editor. 
For now with Gutenberg enter the codes directly.
<h3>Configuration</h3>
No configuration is necessary.
Considering that this plugin, like others working with “markdown”, parsing the page every time I load it, I highly recommend using a caching plugin.
Customizing Footnote Layout
If you want the footnote number to be logically separated from the note (for CSS targeting) but want to prevent unwanted line breaks or extra spacing caused by WordPress’s automatic paragraphs, you can add the following CSS to your theme:
<pre><code>/* Ensure the footnote stays inline or as a specific block */
p > span.footnote {
 display: inline-block;
}

/* Remove extra spacing from the paragraph containing the footnote */
p:has(> span.footnote) {
 margin-bottom: 0;
 margin-top: 0;
 padding: 0;
}
</code></pre>

Blank Footnotes

Simple plugin to show footnotes using markdown notation.

Andrew Nacin

Create simple, elegant footnotes on your site. Use the <code>[ref]</code> shortcode and the plugin takes care of the rest.
Example usage: <code>Lorem ipsum. [ref]My note.[/ref]</code>
If you paginate your posts, you can optionally move your footnotes below your page links. Look under Settings > Reading. Footnotes will still appear as normal for posts that are unpaginated.

Simple Footnotes

Create simple, elegant footnotes on your site. Use the [ref] shortcode and the plugin takes care of the rest.

Blank Footnotes vs Simple Footnotes