linewbie

WP Post Icon is a Free and Open Source WordPress plugin which is enable blog authors to upload and automatically insert topic icons or images in to your posts on the fly. You can control the position of the icon. Just select which image to display when you are writing a post, it will be automatically displayed.
<a href="http://www.linewbie.com/attach-diy/files/wp-post-icon.zip" rel="nofollow ugc">Download now!</a>
Features:
<ul>
<li>Automatically insert your topic icons in to your blog posts.</li>
<li>Very little manual work is required, just select which image to display when you are writing a new post.</li>
<li>
You could also use no image at all.
</li>
<li>
<a href="http://www.linewbie.com/sf-forum?forum=8&page=1" rel="nofollow ugc">Support</a>
</li>
<li><a href="http://www.linewbie.com/2008/02/wp-post-icon.html" rel="nofollow ugc">Version History</a></li>
<li><a href="https://wordpress.org/extend/plugins/wp-post-icon/faq/" rel="ugc">FAQ</a></li>
<li><a href="https://wordpress.org/extend/plugins/wp-post-icon/installation/" rel="ugc">Installation</a></li>
</ul>

WP Post Icon

Enables blogs authors to upload and select topic icons or images and have it automatically show up in their blog post.

Joris van Montfort

Add icons to any rich text field in the WordPress block editor. Insert icons inline in paragraphs, headings, lists, buttons, or use the dedicated single icon block.
<h4>Features</h4>
<ul>
<li>Icon picker – Select icons from a searchable popup in the block editor toolbar.</li>
<li>Font Awesome included – Ships with Font Awesome 4.7, 5.x and 6.x. Choose your preferred version from the settings.</li>
<li>Custom SVG icon set – Upload your own SVG icons via a drag & drop uploader in the plugin settings. This is the recommended approach for the best performance.</li>
<li>Single icon block – A dedicated block with font size, color, alignment and spacing options.</li>
<li>ACF integration – Adds a “JVM Icon” field type for Advanced Custom Fields.</li>
</ul>
<a href="https://nl.wordpress.org/plugins/jvm-rich-text-icons/?preview=1" rel="nofollow ugc">See it in action</a>
<h4>How it works</h4>
Pick an icon from the toolbar while editing any rich text field. The plugin inserts a small HTML tag that gets styled by the chosen icon set.
<h4>Why use a custom SVG icon set?</h4>
When you use a custom SVG icon set, the plugin defaults to inline SVG rendering. This is a great choice for performance! Google PageSpeed Insights will thank you.
<ul>
<li>Better page speed – No render-blocking CSS or font files to download. Icons are part of the HTML itself.</li>
<li>Only loads what you use – Unlike Font Awesome which loads CSS for hundreds of icons, inline SVG only includes the icons that are actually on the page.</li>
<li>No external requests – Everything is served inline, so there are no extra HTTP requests for font or CSS files.</li>
<li>Inherits text color – Icons automatically use the surrounding text color, no extra CSS needed.</li>
<li>Fully reversible – The stored content in the database is not modified. You can switch between render technologies at any time from the plugin settings if you want to.</li>
</ul>
Alternative render technologies (CSS masks, ::before / ::after pseudo-elements) are also available for custom SVG icons if your use case requires it.
<h4>For developers</h4>
The plugin provides several filter hooks to customize its behavior. You can load your own icon set, CSS file, or change the icon class prefix.
Load a custom icon set file
<pre><code>add_filter( 'jvm_richtext_icons_iconset_file', function($file) {
 return get_stylesheet_directory() . '/path_to_my/icons.json';
});
</code></pre>
Load a custom CSS file
<pre><code>add_filter( 'jvm_richtext_icons_css_file', function($cssfile) {
 return get_stylesheet_directory_uri() . '/path_to_my/cssfile.css';
});
</code></pre>
To disable the default CSS file entirely:
<pre><code>add_filter( 'jvm_richtext_icons_css_file', '__return_false');
</code></pre>
Change the icon class prefix
<pre><code>add_filter( 'jvm_richtext_icons_base_class', function() {
 return 'my-custom-css-class-name';
});
</code></pre>
Disable the settings screen
<pre><code>add_filter( 'jvm_richtext_icons_show_settings', '__return_false');
</code></pre>
Please note that if you are loading a custom icon set with the plugin hook: <code>jvm_richtext_icons_css_file</code>, you should make sure the plugin is not set to My SVG uploads as this setting does not load any CSS file.

JVM Rich Text Icons

Thank you so much for the plugin, Joris! I am using a modded version of this plugin to insert a custom icon pack that I created. It was so easy to configure.

You have my utmost respect for this amazing plugin.

Incredible and Highly Extensible

Even though the plugin could not be activated due to a syntax error (which I fixed it - to be more accurate - bypassed it), it eliminates the need for me to create a similar block with ACF Pro for my projects, so thank you for this plugin.

Does one job, and does it well.

I can imagine something like this becoming part of core. Very well developed essential addon for the block editor

great gutenberg addon

Insert icons anywhere in your content — inline in text, headings, buttons, or as a standalone block.

WP Post Icon vs JVM Rich Text Icons