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Getting started with extension development

WooCommerce extensions are WordPress plugins that extend or enhance the functionality of WooCommerce. This guide will help you understand the WooCommerce extension ecosystem and get started building your first extension.

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What are WooCommerce extensions?

WooCommerce extensions are regular WordPress plugins with special capabilities that integrate with WooCommerce’s core functionality. They follow all standard WordPress plugin conventions while leveraging WooCommerce’s extensive API, hooks, and filters.

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What extensions can do

Extensions can enhance WooCommerce in countless ways:
  • Payment gateways: Add new payment methods and integrate with payment providers
  • Shipping methods: Create custom shipping calculators and integrate with shipping carriers
  • Product types: Define new product types with unique behavior and attributes
  • Admin tools: Add reporting, analytics, bulk editing, and management features
  • Frontend enhancements: Customize the shopping experience, product display, and checkout flow
  • Integrations: Connect WooCommerce with third-party services, CRMs, and marketing platforms
  • Notifications: Send emails, SMS, or push notifications for various store events
  • Tax calculators: Implement custom tax calculation logic

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The WooCommerce marketplace

The WooCommerce Marketplace is the official distribution platform for WooCommerce extensions. Here’s what you need to know:

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Benefits of the marketplace

  • Built-in discovery: Merchants find extensions through the WooCommerce admin and marketplace
  • Trusted platform: Extensions are reviewed for quality, security, and compatibility
  • Revenue opportunity: Sell your extensions to thousands of WooCommerce merchants
  • Support infrastructure: Access to support tools, documentation, and developer resources
  • Automatic updates: Merchants receive updates through the WordPress admin

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Marketplace requirements

Extensions submitted to the WooCommerce Marketplace must:

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Development environment setup

Before building WooCommerce extensions, set up a proper development environment.

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Prerequisites

1

Install WordPress

You’ll need a local WordPress installation. Popular options include:
2

Install WooCommerce

Install and activate the WooCommerce plugin on your WordPress site. You can install it from:
3

Enable debugging

Add these lines to your wp-config.php file to enable debugging:
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
define( 'SCRIPT_DEBUG', true );
This will log errors to wp-content/debug.log and use unminified JavaScript files.
4

Set up version control

Initialize a Git repository for your extension to track changes and collaborate with others.

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Development workflow

A typical WooCommerce extension development workflow follows these stages:

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1. Planning and design

  • Define your extension’s purpose and core features
  • Research existing solutions and identify gaps
  • Plan the user experience for both merchants and customers
  • Document the technical requirements and dependencies

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2. Development

  • Create the plugin structure and files
  • Implement core functionality using WooCommerce hooks and APIs
  • Follow WordPress coding standards
  • Write secure, performant code
  • Add internationalization support

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3. Testing

Testing is crucial for extension quality. Use the Quality Insights Toolkit (QIT) to test your extension against different versions of PHP, WooCommerce, and WordPress.
Test your extension thoroughly:
  • Functionality testing: Verify all features work as expected
  • Compatibility testing: Test with different themes, plugins, PHP versions, and WooCommerce versions
  • Performance testing: Ensure your extension doesn’t slow down the store
  • Security testing: Check for vulnerabilities and data leaks
  • User testing: Get feedback from actual merchants

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4. Documentation

Create comprehensive documentation:
  • Installation instructions: How to install and activate the extension
  • Configuration guide: How to set up and configure features
  • User guide: How to use the extension’s features
  • Developer documentation: Hooks, filters, and APIs your extension provides
  • Troubleshooting: Common issues and solutions

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5. Release and maintenance

  • Create a changelog file documenting all changes
  • Version your extension following semantic versioning
  • Submit to the WooCommerce Marketplace or distribute independently
  • Provide ongoing support and bug fixes
  • Release updates for new WooCommerce versions

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Key development concepts

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Check if WooCommerce is active

Most extensions should only run when WooCommerce is active. Always check before initializing your extension: 
if ( ! in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) ) {
    return;
}
Learn more in Check if WooCommerce is active.

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Use WooCommerce APIs

Leverage WooCommerce’s built-in functionality instead of building from scratch:
  • Product API: Query and manipulate products
  • Order API: Work with orders and order data
  • Settings API: Add settings pages and fields
  • Customer API: Access customer data and purchase history
  • REST API: Build integrations and headless commerce solutions

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Extend with hooks and filters

WooCommerce provides hundreds of actions and filters for customization: 
// Add custom content after product title
add_action( 'woocommerce_single_product_summary', 'add_custom_content', 6 );

function add_custom_content() {
    echo '<div class="custom-content">Custom content here</div>';
}

// Modify product price
add_filter( 'woocommerce_product_get_price', 'modify_product_price', 10, 2 );

function modify_product_price( $price, $product ) {
    // Your custom pricing logic
    return $price * 1.1; // Example: 10% markup
}

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Avoid internal code

Never use internal WooCommerce code in your extensions. Classes in the Automattic\WooCommerce\Internal namespace and code marked with @internal annotations are for WooCommerce core use only. Backwards compatibility is not guaranteed.
Internal code may change, be renamed, or be removed in any future release without notice.

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Next steps

Now that you understand the basics of WooCommerce extension development:
  1. Follow the first extension tutorial to build a simple extension
  2. Review extension development best practices
  3. Learn about the WooCommerce Settings API
  4. Explore WooCommerce hooks and filters
  5. Study the WooCommerce codebase for real-world examples

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Additional resources

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