WordPress Block Theme Development: The Future of Full Site Editing

Learn everything about WordPress block theme development — the foundation of Full Site Editing (FSE). Discover its structure, benefits, tools, and how to build your own block-based theme from scratch.

Introduction: What Is a WordPress Block Theme?

WordPress block themes are a new generation of themes that use blocks for every part of a website — headers, footers, sidebars, and content. Introduced with Full Site Editing (FSE) in WordPress 5.9, block themes are revolutionizing how developers and non-developers build websites.

Unlike classic themes that rely heavily on PHP templates, block themes are powered by HTML files and block markup. This allows users to customize their entire site through the Gutenberg editor, with no need for additional coding or theme files.

Why Choose Block Theme Development?

1. Total Design Freedom with Full Site Editing

Create, edit, and rearrange any part of your site — all visually, using blocks.

2. Minimal Code, Maximum Control

Less PHP, more JSON and HTML means easier updates and faster development.

3. Future-Proofing Your Website

Block themes are built for modern WordPress. As FSE evolves, block-based themes will become the standard.

4. Better Performance and SEO

Clean HTML, optimized layouts, and fewer heavy dependencies lead to faster load times and better SEO rankings.

Key Components of a WordPress Block Theme

File	Purpose
style.css	Basic theme metadata and optional fallback styles
theme.json	Controls global styles, color palettes, font settings, spacing, etc.
templates/	Folder with HTML files like index.html, page.html, single.html
parts/	Reusable layout parts like header.html, footer.html, sidebar.html
patterns/	Pre-designed block layouts (optional but recommended)
functions.php	Minimal use, mainly for enqueueing assets or registering features

Step-by-Step Guide to Developing a Block Theme

Step 1: Set Up a WordPress Environment

Use tools like LocalWP, XAMPP, or DevKinsta to develop locally.

Step 2: Create Your Theme Folder

In /wp-content/themes/, create a folder for your block theme (e.g., myblocktheme).

Step 3: Add Required Files

At minimum, include:

• style.css
• theme.json
• templates/index.html

Step 4: Define Global Styles in theme.json

This is where you control fonts, colors, spacing, and more.

{
  "version": 2,
  "settings": {
    "color": {
      "palette": [
        { "slug": "primary", "color": "#000000", "name": "Black" }
      ]
    }
  }
}

Step 5: Create HTML Templates

Place index.html, page.html, etc., in the /templates/ folder with Gutenberg block markup.

Step 6: Add Reusable Parts

Use the /parts/ folder for headers, footers, and sections that appear across multiple templates.

Step 7: Add Block Patterns (Optional but Powerful)

Include pre-built layouts users can insert anywhere in the site editor.

Step 8: Test and Validate

Check your theme in the Site Editor under Appearance > Editor. Make sure templates and global styles work as expected.

Tools to Use in Block Theme Development

• Gutenberg Editor (for visual block editing)
• Block Theme Generator (https://wordpress.org/block-theme-generator)
• Theme.json Reference: https://developer.wordpress.org
• Block Theme Checker Plugin
• VS Code + WordPress Snippet Extensions

Best Practices for Block Theme Developers

• Use theme.json for all global styling — avoid inline styles or external CSS files
• Follow WordPress naming conventions and folder structure
• Create accessible designs with semantic HTML
• Avoid unnecessary dependencies and third-party scripts
• Test responsiveness on all screen sizes
• Optimize patterns and templates for reusability

For More Information: Cash Flare Digital

FAQs: 

1. What’s the difference between classic and block themes?
Classic themes rely on PHP templates and the Customizer, while block themes use HTML templates and Full Site Editing.

2. Do I need to know PHP to build a block theme?
Not much. Block themes are built mostly with HTML, JSON, and Gutenberg blocks.

3. Can I convert a classic theme into a block theme?
Yes, but it requires restructuring and replacing PHP templates with HTML block templates.

4. Are block themes mobile responsive?
Yes, block themes support responsive design out of the box using flexible blocks and container settings.

5. What is the theme.json file used for?
It defines global styles and theme settings like fonts, colors, spacing, and more.

6. Can I use a page builder with a block theme?
Block themes are optimized for Gutenberg. Using other page builders may cause conflicts.

7. Are block themes good for SEO?
Yes. They produce clean, lightweight HTML and integrate well with SEO plugins like Yoast or Rank Math.

8. Is it possible to sell a block theme?
Yes. Block themes can be submitted to the WordPress Theme Directory or sold commercially.

9. Do block themes support WooCommerce?
Yes, WooCommerce supports block-based templates and product blocks.

10. Can beginners develop a block theme?
Yes. With basic HTML knowledge and Gutenberg familiarity, anyone can start building.