Pavel

The “Light Code Block” plugin is a simple and lightweight solution for inserting and displaying code snippets in posts and pages. 
It works by adding a custom “LC” button to the TinyMCE (Classic) editor or a code block in the Gutenberg editor.
The inserted code will be shown on the front end in a clean, readable format.
<h3>Usage</h3>
<ul>
<li>Install and activate the plugin.</li>
<li>Go to the post or page edit screen.</li>
<li>In the TinyMCE (Classic) editor, click the “LC” button in the toolbar.</li>
<li>In the popup window that opens, paste or write your code, and click OK.</li>
<li>Save or update your post.</li>
</ul>
The code will be saved inside a special block and displayed on the front end within a <code><pre></code> tag with the class <code>mce-simple-code-block</code> (i.e., <code><pre class="mce-simple-code-block">...</pre></code>).
To insert code using the Gutenberg editor, you first need to add a Classic (TinyMCE) block, and then use it to insert your code.

Light Code Block

The "Light Code Block" plugin is the simplest and lightest plugin for inserting and displaying code.

kioub

With support for the new block editor in WordPress 5.0!
SyntaxHighlighter Amplified allows you to easily post syntax-highlighted code to your site without losing its formatting or making any manual changes. It uses the <a href="https://github.com/scrivo/highlight.php" rel="nofollow ugc">highlight.php package by Geert Bergman</a> to render code on the server-side so it has no depedencies on extrenal Javascript libraries thus is compatible with AMP pages.
For a live demo, see <a href="https://www.javacodegeeks.com/syntaxhighlighter-amplified/" rel="nofollow ugc">this demo page</a>.
For a list of supported languages (most widely used languages are supported), see the <a href="http://en.support.wordpress.com/code/posting-source-code/" rel="nofollow ugc">WordPress.com support document</a>.
Development of this plugin is <a href="https://github.com/kioub78/syntaxhighlighter-amplified" rel="nofollow ugc">on GitHub</a>. See <a href="https://github.com/kioub78/syntaxhighlighter-amplified/issues" rel="nofollow ugc">list of current issues</a> with the plugin. Please feel free to file any additional issues or requests that you may come across. <a href="https://github.com/kioub78/syntaxhighlighter-amplified/pulls" rel="nofollow ugc">Pull requests</a> are welcome.
Translation of the plugin into different languages is on the <a href="https://translate.wordpress.org/projects/wp-plugins/syntaxhighlighter-amplified" rel="nofollow ugc">translation page</a>.
<h4>CREDITS</h4>
This is a fork of <a href="https://github.com/Automattic/syntaxhighlighter" rel="nofollow ugc">SyntaxHighligher Evolved</a> by <a href="https://alex.blog/" rel="nofollow ugc">Alex Mills</a> (Viper007Bond), which is also <a href="https://wordpress.org/plugins/syntaxhighlighter/" rel="ugc">available on WordPress.org</a>. Copyright (c) 2018 Alex Mills. Licensed under GPL 2.0 or later.
<a href="https://github.com/scrivo/highlight.php" rel="nofollow ugc">highlight.php</a> is released under the BSD 3-Clause License. Copyright © 2006-2013, Ivan Sagalaev (maniac@softwaremaniacs.org), highlight.js (original author). Copyright © 2013, Geert Bergman (geert@scrivo.nl), highlight.php

SyntaxHighlighter Amplified

Easily post syntax-highlighted code to your site without having to modify the code at all. Compatible with AMP pages.

Light Code Block vs SyntaxHighlighter Amplified