WordPress Theme Frameworks and Starter Themes

_s or underscores

Underscores is a starter theme for WordPress made by Automattic claiming to provide a 1000 hours head start. It is a theme meant for hacking and best not used as a parent theme.
Here’s what’s currently in _s:

• A just right amount of lean, well-commented, modern, HTML5 templates.
• A helpful 404 template.
• A sample custom header implementation in inc/custom-header.php that can be activated by uncommenting one line in functions.php and adding the code snippet found in the comments of inc/custom-header.php to your header.php template.
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• Custom template tags in inc/template-tags that keep your templates clean and neat and prevent code duplication.
• Sample theme options in /inc/theme-options/ that can can be activated by uncommenting one line in functions.php.
• Some small tweaks in /inc/tweaks.php that can improve your theming experience. They can be activated by uncommenting one line in functions.php.
• Keyboard navigation for image attachment templates. The script can be found injs/keyboard-navigation.js and is enqueued from the image attachment template, image.php.
• A script at js/small-menu.js that makes your menu a toggled dropdown for small screens (like your phone) ready for CSS artistry. It’s enqueued in functions.php.
• 5 sample CSS layouts in /layouts: Two sidebars on the left, two sidebars on the right, a sidebar on either side of your content, and two-column layouts with sidebars on either side.
• Smartly organized starter CSS in style.css that will help you to quickly get your design off the ground.

Hybrid Core

Hybrid Core is a WordPress theme development framework for creating solid parent themes. It allows theme developers to forget about all the complex functionality and dive straight into coding their theme’s HTML, CSS, and JavaScript.
The purpose of Hybrid Core is to have a solid PHP code base for theme developers to build from. It is a modular framework that allows the developer to pick and choose commonly-used features in themes.
This is a very popular theme framework which forms the basis for many other theme developers like DevPress, AlienWP and HappyLoops.

Roots Theme

Roots is a starting WordPress theme based on HTML5 Boilerplate & Bootstrap from Twitter. Roots boasts of the following features:

• Multilingual ready and WPML compatible. Roots already includes translations for: English, Spanish, French, Italian, Dutch, Brazilian Portuguese, Macedonian, Finnish, Danish, Turkish, Swedish, Bulgarian, Norwegian, Catalan, Polish, Hungarian, Russian
• ARIA roles on the main site components
• Blog posts are based on the hNews microformat as recommended by Readability’s Article Publishing Guidelines
• Most of HTML5 Boilerplate’s awesome .htaccess is automatically generated

Bones

Bones is a HTML5 WordPress starter theme. Bones is bare and as minimalistic as possible. It’s meant to be used as a per-project template, this means no Child Themes. Bones comes ready to roll with a unique LESS/Sass setup that serves minimal resources to smaller screens and scales up depending on your viewport. It also makes custom post typed and custom dashboard functions easy. It has found some popularity that there are other theme frameworks built on it like WP Foundation and WP Bootstrap.

Other WordPress theme frameworks and starter themes:

* Reverie – HTML5 Responsive WordPress Framework based on the Power of Foundation.
* Starkers – A bare-bones WordPress theme created to act as a starting point for the theme designer. Free of all style, presentational elements, and non-semantic markup, Starkers is the perfect ‘blank slate’ for all your WordPress projects.
* StartBox – A theme framework for free with premium child themes. Has gained actively development again after being backed by WebdevStudios
* Skeleton -Simple and responsive WordPress theme framework from Simple Themes.