John

This plugin enables you to highlight syntax using the PEAR Text_Highlighter class. Other syntax highlighters that use GeSHi have slower rendering speeds which will increase your page load time. However, this plugin gives you the speed and efficiency provided by the PEAR developers. You even have the option of enabling or disabling the line numbers as well as specifying your own style.

Ion Snytax Highlighter

This plugin allows users to highlight code.

Akinori MUSHA

This plug-in adds download facility to 
<a href="https://wordpress.org/extend/plugins/wp-syntax/" rel="ugc">WP-Syntax</a>, putting a 
pretty caption to each syntax highlighted code snippet, which contains 
a permalink anchor and a couple of action buttons: “raw” and 
“download”.
The usage is easy. You just put an attibute <code>filename="..."</code> to 
a <code><pre></code> element and the snippet will have a caption.
I strongly recommend that you use the <a href="https://wordpress.org/extend/plugins/tinymce-valid-elements/" rel="ugc">TinyMCE Valid 
Elements</a> 
plug-in to make the non-standard attributes of the <code><pre></code> element 
treated as valid and get preserved in the visual editor. Configure it 
so that the <code>pre</code> element can have the following attributes:
<ul>
<li><code>class</code></li>
<li><code>dir</code></li>
<li><code>escaped</code></li>
<li><code>filename</code></li>
<li><code>highlight</code></li>
<li><code>id</code></li>
<li><code>lang</code></li>
<li><code>line</code></li>
<li><code>style</code></li>
<li><code>title</code></li>
<li><code>wrap</code></li>
</ul>
You can alter the visual style of captions with CSS via admins menu. 
This plug-in was first developed for PHP 5.2.12 and is currently 
tested only with 5.4. It will never work with PHP 4.
<h3>License</h3>
Copyright (c) 2010-2024 Akinori MUSHA
All rights reserved.
Redistribution and use in source and binary forms, with or without 
modification, are permitted provided that the following conditions 
are met:
<ol>
<li>
Redistributions of source code must retain the above copyright 
notice, this list of conditions and the following disclaimer.
</li>
<li>
Redistributions in binary form must reproduce the above copyright 
notice, this list of conditions and the following disclaimer in the 
documentation and/or other materials provided with the distribution.
</li>
</ol>
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS “AS IS” AND 
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
SUCH DAMAGE.

WP-Syntax Download Extension

This plug-in makes WP-Syntax highlighted code snippets downloadable from nice captions.

Ion Snytax Highlighter vs WP-Syntax Download Extension