Andrew Parman

This plugin adds a Gutenberg block called <code>IECST Highlighter</code>. After entering a code snippet in the editor, 
the output will be rendered with a syntax highlighting style selected in the IECST Highlighter Settings.
This plugin uses the <a href="https://github.com/PhioAutomation/phio-highlighter" rel="nofollow ugc">Phio Highlighter</a> which is distributed 
with an MIT License, https://highlighter.phioautomation.com/LICENSE.txt.
Development of this plugin is on <a href="https://github.com/PhioAutomation/phio-highlighter" rel="nofollow ugc">Github</a>.

IECST Highlighter

Display beautiful code snippets using the Phio Highlighter for the IEC 61131-3 Structured Text language

Rachel Baker

This plugin uses the <a href="http://projects.serenity.de/textmate/" rel="nofollow ugc">Sunburst theme</a>, a colorful and high contrast dark theme to highlight your code syntax with <a href="http://softwaremaniacs.org/soft/highlight/en/" rel="nofollow ugc">Highlight.js</a>. Highlight.js is accurate, fast, lightweight and easy to use.
Usage
Short-code method:
<ol>
<li>From within a WordPress page or post, wrap the <code>[prettify][/prettify]</code> shortcode around the code snippet you wish to highlight.</li>
<li>You can specify a language by specifying the language extension inside the shortcode. 
Example: 
[prettify class=”html”][/prettify]</li>
<li>The shortcode will work from within either the Visual or HTML editor.</li>
</ol>
Non-short-code method:
<ol>
<li>
Wrap your code snippets in “
.
</li>
<li>You can specify a language by specifying a class in the <code>element. 
Example: 
<pre><code class="html"></code></li>
</ol>
Sunburst Only
This plugin only contains the CSS file for the Sunburst theme syntax highlighting formatting, because it is the best dark syntax theme. If (for some reason) you wanted to highlight your code using a different theme, there are other syntax highlighting themes available in the <a href="http://softwaremaniacs.org/media/soft/highlight/test.html" rel="nofollow ugc">Highlight.js Theme Gallery</a>
Languages Supported:
<ul>
<li>Bash</li>
<li>C#</li>
<li>C++</li>
<li>CSS</li>
<li>Diff</li>
<li>HTML, XML</li>
<li>Ini</li>
<li>Java</li>
<li>JavaScript</li>
<li>PHP</li>
<li>Perl</li>
<li>Python</li>
<li>Ruby</li>
<li>SQL</li>
</ul>

Sunburst Code Prettify

Uses Highlight.js with the Sunburst syntax theme to elegantly highlight code.

IECST Highlighter vs Sunburst Code Prettify