Blog

Full Site Editing (FSE) for Real Sites: Patterns, Template Parts, theme.json

September 4, 2025 No comments yet

With the advent of Full Site Editing (FSE), WordPress has stepped into a new era of design and development, offering more control and flexibility to users and developers alike. This revolutionary approach empowers everyone to modify virtually every aspect of their site—beyond just posts and pages—directly within the Block Editor. Key components of FSE such as patterns, template parts, and the theme.json file are instrumental in building dynamic, custom, and user-friendly WordPress websites. Let’s explore how each of these pieces plays a crucial role in real-world scenarios and how to effectively use them in your next WordPress project.

Understanding Full Site Editing (FSE)

Full Site Editing allows site owners to visually edit and manage their site layout and design with blocks. It blends the creative ease of using blocks with the structure and customization typically found in traditional theming. It’s not just an evolution in design approach—FSE is a holistic change in WordPress theme development.

Patterns: Building Blocks with a Purpose

Patterns are predefined collections of blocks designed to streamline design and functionality. They allow theme developers and users to create repeatable elements such as Call-To-Actions (CTAs), testimonials, service listings, or headers across pages without manually recreating the layout each time.

Real sites benefit tremendously from patterns, especially in scenarios where layout consistency is essential. For instance, a business website with multiple landing pages may use pattern blocks to ensure branding and structure remains standardized.

Some key reasons to use Patterns:

  • Time-saving: Quickly insert full sections without manual customization.
  • Uniform Design: Maintain design consistency across the website.
  • User-friendly: Easily accessible to users with little coding experience.

Patterns can be defined in the patterns folder of a block theme and registered in the code or made available via the Pattern Directory for broader usage. Each pattern comes with its metadata allowing you to categorize and label them for easier discovery.

Template Parts: The Blueprint of Reusable Layouts

Template parts are reusable sections that are part of a theme’s structure, such as headers, footers, or sidebar areas. By isolating these segments into template parts, you create modular pieces of a site that can be reused across different templates or updated globally from one location.

Imagine a client wants to update their site’s navigation bar across dozens of pages. Instead of editing each page individually, they can update a single header template part—and the change propagates everywhere.

Common examples of template parts in real sites include:

  • Header – Contains logo, navigation, and perhaps a search bar.
  • Footer – Includes copyright, legal links, and social icons.
  • Sidebar – Features recent posts, call-to-actions, or ad spaces.

Template parts are defined within the parts or templates/parts directory inside a block theme. They’re usually pulled into larger templates like home or blog archive layouts, enhancing modularity in design.

theme.json: Centralized Site Configuration

One of the most powerful additions to Full Site Editing is the theme.json configuration file. This file acts as the single source of truth for a theme’s settings, styles, and customization options. It defines everything from typography, color palettes, block settings, to spacing and layout controls.

Through theme.json, site developers can:

  • Control and restrict the styling options available to content creators.
  • Set default values for font sizes, colors, and block behavior.
  • Customize responsiveness and layout constraints.

In a real-world use case, a media company might use a robust theme.json to impose strict branding rules ensuring logo colors and fonts remain aligned across hundreds of articles penned by multiple authors.

Benefits of theme.json:

  • Performance: Less reliance on complex CSS files.
  • Consistency: Unified styles and spacing sitewide.
  • Developer Control: Avoid design creep or inconsistent block use.

Using FSE in Real Projects

The true power of FSE lies in its ability to blend modular development with visual editing. On production websites, this enables faster iteration, easier branding updates, and improved collaboration between developers and content creators.

For example, an eCommerce website can use patterns for product listings and featured sections, template parts for cart and checkout layouts, and theme.json to enforce typographic consistency across product descriptions, blogs, and policies.

Moreover, FSE opens doors to faster prototyping. Clients can see near-final designs simply by selecting patterns and blocks, while developers focus on logic and custom block development—leading to efficient project timelines and better results.

Best Practices for Implementing FSE

  • Plan site architecture: Determine reusable parts and patterns early in the project.
  • Use the Pattern Directory: Take advantage of existing patterns for inspiration or direct use.
  • Limit excess CSS: Rely on theme.json to avoid bloated stylesheets.
  • Test on staging: FSE features can have a learning curve and technical quirks—thoroughly test before deploying.

FAQ

  • Q: Is Full Site Editing suitable for all types of WordPress sites?
    A: Yes and no. FSE is great for new projects or full redesigns, but legacy themes may require significant rework to adopt FSE fully.
  • Q: Can patterns be imported into any site?
    A: Patterns can be shared using the Pattern Directory or as part of a custom theme and then imported or reused.
  • Q: How does theme.json affect child themes?
    A: theme.json settings from parent themes can be overridden or merged in child themes using their own theme.json file.
  • Q: Is FSE backward-compatible with older WordPress versions?
    A: FSE features are officially supported from WordPress 5.9 onward. Older versions may not support template editing or block-based themes entirely.
  • Q: Can I still use PHP in FSE themes?
    A: While HTML templates and theme.json define most structures, PHP can still be employed for advanced logic, filters, and functionality.

Full Site Editing is not just another feature—it’s the future of WordPress theme development. By mastering patterns, template parts, and theme.json, developers and site owners can craft responsive, consistent, and visually compelling websites that are easier to maintain and enhance. The learning curve may be steep, but the dividends in flexibility and control make it worthwhile for any serious WordPress professional.