Allon Sacks

Not only for developers. 
Create content blocks for reusable global content. Supports revisions. With input fields for raw HTML, JS, and CSS without worrying about auto formatting, with an option to also use the usual formatted WordPress tinyMCE editor.
This plugin let’s you create modular content blocks the right way:
<ol>
<li>Content blocks are a post type.</li>
<li>Allows you to add HTML, CSS, and JS in separate blocks using ACE editor with code completion and error notifications.</li>
<li>WordPress WYSIWYG editor optional.</li>
<li>Revisions(!) You can change your WordPress content, HTML, CSS, and JS and then go back to a previous state the same as you can with the out of the box wordpress post revisions.</li>
<li>Use a shortcode to add the blocks in posts, pages, CPT’s, widgets, and in your theme files.</li>
<li>Preview your content.</li>
<li>Easily import & export using the default WordPress XML import/export tool.</li>
</ol>
Using content blocks you can create blocks of content to display globally. Change the block and any page the content block is embedded on will reflect the changes.
Use Cases:
<ul>
<li>
The WordPress WYSIWYG editor and even the text editor is often unpredictable not adding line breaks when wanted, or losing formatting after editing a post: 
Just create a content block calling it “br” using only the HTML box and put in the box. The shortcode “[dcb name=br]” can then be used whenever you want to make sure that you have a line break.
</li>
<li>
You may have multiple “thank you” pages for different LP’s. When you start new campaigns or want to add new conversion code (or delete an old conversion code), you need to go to each ty page and add/delete the conversion code: 
With modular content you can maintain all your conversion codes in one block and then just put the same shortcode in all ty pages. Also, with the regular WordPress editor you cannot always safely embed conversion code in the post itself and rely on using a separate template. This plugin solves all these issues.
</li>
<li>
Ads: 
Use the content blocks to manage your ads in one place. Create a content block per ad, then use a shortcode in your post content/theme files/widgets where you want to display each ad.
</li>
<li>
There are many more use cases, these were just a few examples. Really you can use content blocks for so many cases and the power it gives you to manage and maintain modular content is necessary on almost any kind of website.
</li>
</ul>
Content Blocks are an easy way for you to create your own shortcodes within the admin and can be used as a minimal shortcode builder.
Dev Content Blocks is created with developers in mind, so while it is simple enough for any WordPress user to use, developers will have added benefit of being able to use raw HTML without it being formatted by wptexturize and wpautop. Think arbitrary HTML in the old text widget (new “Custom HTML” widget). Here paragraphs are NOT added automatically. 
Also, as CSS and JS can easily be added here without fear of it losing it’s formatting, this plugin let’s you create and manage your own shortcodes. You can easily create shortcodes (the type that do not accept arguments) and manage them in one place in the admin instead of creating them in the theme or as a separate plugin per shortcode.
You can actually add CSS and JS in the HTML box but, for convenience this plugin has separate optional CSS and JS boxes to allow you to separate your content and code. 
The output of the shortcode is: 
1. Content from the WordPress editor if it is enabled. (Note, here wptexturize and wpautop are used). 
2. Content from the HTML box. 
3. The CSS code wrapped in a style tag. 
4. The JS code wrapped in a script tag. 
(“if(typeof(jQuery) !== ‘undefined’) {$ = jQuery.noConflict();}” is prepended to the script.)
Please Note. Dev Content Blocks lets you use raw HTML, JS, and CSS therefore be careful if copying and pasting from random web pages as in order to allow you maximum control with the content blocks, you will be able to paste JS that is not entirely validated.
<h3>Future Versions</h3>
<ol>
<li>Enable/disable each box in the “Content Block Code” section.</li>
<li>More Page builder support</li>
<li>Variables to be passed in the shortcode</li>
<li>Option to enqueue other CSS & JS files when a block is used</li>
<li>Preview in a light box on the admin screen</li>
<li>Options for incorporating and using the featured image</li>
<li>Add an option to change the order of the HTML box vs. the WP editor</li>
<li>Add an option to turn off formatting in the WP editor</li>
<li>Add an option to enqueue the CSS and JS instead of outputting it in the HTML</li>
<li>Widget</li>
<li>Button in tinyMCE to add shortcodes</li>
<li>Show shortcodes in main Dev Content Blocks screen</li>
<li>Localization and language support</li>
<li>When leaving or refreshing the admin page users should receive a prommpt if they have unsaved changes in the code boxes</li>
<li>All above are under consideration and may or may not be added. Please feel free to email me or write a comment here in the reviews or support section with bugs and/or suggestions.</li>
</ol>

Dev Content Blocks

This plugin is really useful when I want to add scripts into specific post/page. Also this makes possible to create some html components with scripts and css easily. I love this!

Really useful!

Content blocks for global content, with revisions. Use HTML without formatting being broken. Not only for devs.

Will Norris

This is a plugin based implementation of Daryl Koopersmith’s modular themes concept and patch 
(<a href="https://core.trac.wordpress.org/ticket/12877" rel="nofollow ugc">#12877</a>). It provides the <code>get_template_module()</code> function, which allows for the creation 
of well-architected themes with highly reusable code. For more on the use of this function, 
read Daryl’s series of posts:
<ul>
<li><a href="http://drylk.com/2010/04/06/modular-themes-why/" rel="nofollow ugc">Modular Themes, Part 1: Why?</a></li>
<li><a href="http://drylk.com/2010/04/06/modular-themes-organization/" rel="nofollow ugc">Modular Themes, Part 2: Theme Organization</a></li>
<li><a href="http://drylk.com/2010/04/06/modular-themes-performance/" rel="nofollow ugc">Modular Themes, Performance</a></li>
</ul>
If you like this method of WordPress theme design, then vote up ticket <a href="https://core.trac.wordpress.org/ticket/12877" rel="nofollow ugc">#12877</a>. The ideal 
scenario is for this functionality to be provided in WordPress core. This plugin is simply a proof 
of concept, and provides an easy way for theme developers to start playing with modular themes. The 
bulk of this plugin is directly from Daryl’s patch. The one exception being the 
 update_template_hierarchy() function, which duplicates much of the template selection logic from 
 wp-includes/theme.php in WordPress core.

Template Modules

Add the infrastructure to enable Daryl Koopersmith's modular theme concept.

Dev Content Blocks vs Template Modules