The Gutenberg block editor transformed WordPress content creation, but the default blocks only cover basic needs. Custom blocks let you give clients sophisticated content components — testimonial carousels, pricing tables, feature grids, CTA sections — that they can use without touching code. Building custom blocks well requires understanding both React and WordPress's Block API. Here is how to approach it.
Understanding the Block Architecture
Every Gutenberg block has two faces: an Edit component (what the editor shows) and a Save function (what gets stored as HTML in the database). The Edit component is a React component with full interactivity — sidebar controls, inline editing, drag-and-drop. The Save function outputs static HTML that WordPress renders on the frontend. This separation is fundamental to how blocks work.
Block registration happens in JavaScript via registerBlockType(), which defines the block's name, attributes (its data model), Edit component, and Save function. The block's metadata is declared in a block.json file that WordPress uses for registration, asset loading, and translation. Always use block.json — it enables lazy loading of block assets, reducing editor overhead.
Setting Up Your Development Environment
The recommended tooling for block development:
- @wordpress/create-block: The official scaffolding tool that generates a complete block plugin with proper build configuration, ESLint setup, and example code. Run
npx @wordpress/create-block your-block-nameto get started. - @wordpress/scripts: Handles webpack bundling, JSX transformation, and CSS processing. It is configured by create-block and handles build and development watch modes.
- wp-env: A Docker-based local WordPress environment for testing blocks. Provides a consistent development environment that matches production behaviour.
Building the Edit Component
The Edit component is where your block comes alive in the editor. Use WordPress's component library — @wordpress/components provides buttons, dropdowns, colour pickers, and form controls that match the editor's design language. For sidebar controls, use InspectorControls to add settings to the block's sidebar panel. For toolbar controls, use BlockControls.
Make content directly editable in the block preview using RichText for formatted text fields. This gives editors a WYSIWYG experience where they type directly into the block rather than filling out form fields. For media selection, use the MediaUpload component to access the WordPress media library. The goal is to make the editor experience feel native — your custom blocks should be as intuitive as the built-in ones.
Dynamic Blocks and Server-Side Rendering
Not all blocks should save static HTML. Dynamic blocks render their output via PHP on the frontend, which is necessary when the output depends on data that changes independently of the editor — latest posts, user-specific content, or data from external APIs. For dynamic blocks, the Save function returns null, and you register a render_callback in PHP that generates the HTML at request time.
Dynamic blocks also avoid the "block validation failed" errors that occur when you update a static block's markup. Since the output is generated by PHP, you can change the rendering without invalidating existing content. For blocks that you expect to evolve over time, dynamic rendering provides more flexibility.
Best Practices for Client-Friendly Blocks
The point of custom blocks is empowering clients to manage their own content. Design blocks that constrain choices to prevent layout breakage. Instead of giving editors full colour freedom, provide a curated palette. Instead of arbitrary sizing, offer "small", "medium", and "large" options. Use block variations and patterns to give editors pre-configured block arrangements that look good by default.
At Born Digital, we build custom Gutenberg blocks as part of our WordPress theme development process. Each block is designed to give clients editorial flexibility while maintaining visual consistency with their brand. The investment in well-built custom blocks pays for itself through reduced support requests and faster content publishing — clients can build sophisticated page layouts without developer assistance.