Alex Mansfield

This plugin allows you to easily add code to your pages and posts without worrying about what the WordPress editor will do to it. You can embed HTML, video embed codes, Paypal forms, Google maps and more. Please note: this plugin will not allow you to run server side scripts such as PHP.
To use the plugin, all you have to do is create a custom field (you can name it anything), place your code in the new custom field, and place the following shortcode into your post where you want the code to go:
<pre><code>[easyembed field="name-of-custom-field"]
</code></pre>

Easy Embed

Allows any code to be easily embedded in posts and pages.

treeflips

Yin Zhongzhen

Simple plugin that automatically copies content in <code><pre></code> and <code><code></code> tags to clipboard (when clicked). Other plugins out there do the same but create a little [COPY] button that you have to aim for. Mine doesn’t require any aiming, just click anywhere on the code block and it copies the whole thing. Customizable hover tooltip lets you know it’s copied.
For sites sharing code-commands, this plugin will save users time from having to highlight and copy-paste bits of text back and forth. It’s especially helpful for large globs of code that scroll off-screen, or when copying on your mobile phone. I’ve added more features to make it more helpful.
Features: 
* Easy aim – click anywhere on text block to copy entire text, no need to aim for tiny text or clipboard icon. 
* Tooltip text customization – change tooltip text. 
* Tooltip color options – customize tooltip background and text colors. 
* Tooltip hover custom CSS – completely restyle the tooltip hover. 
* Tooltip function custom CSS – apply tooltip function to other CSS classes. Allowing copy function on any content block, not only code blocks.

Easy Embed vs Code Click to Copy