How to Extend WooCommerce REST API for Custom Apps

Extending the WooCommerce REST API allows you to connect custom apps, mobile applications, or third-party services with your WooCommerce store. This guide covers creating custom endpoints, modifying responses, and securing your API for tailored e-commerce solutions.

🔧 Prerequisites

WooCommerce installed (v4.5+ for best compatibility)
Basic PHP & WordPress REST API knowledge
A development environment (Local by FlyWheel, XAMPP, etc.)
Authentication method (API keys, JWT, or OAuth). Our YouTube channel; https://www.youtube.com/@easythemestore

🚀 Method 1: Register Custom Endpoints

Step 1: Create a Plugin

Add this to wp-content/plugins/woocommerce-custom-api/woocommerce-custom-api.php:

<?php
/**
 * Plugin Name: WooCommerce Custom API
 * Description: Extends WooCommerce REST API for custom apps.
 * Version: 1.0
 */

if (!defined('ABSPATH')) exit;

add_action('rest_api_init', 'register_custom_woocommerce_endpoints');

function register_custom_woocommerce_endpoints() {
    register_rest_route('wc/v3', '/custom-products', [
        'methods' => 'GET',
        'callback' => 'get_custom_products',
        'permission_callback' => '__return_true' // Open endpoint (secure in production!)
    ]);
}

function get_custom_products($request) {
    $args = [
        'status' => 'publish',
        'limit' => 10,
    ];
    $products = wc_get_products($args);
    return array_map(function($product) {
        return [
            'id' => $product->get_id(),
            'name' => $product->get_name(),
            'price' => $product->get_price(),
            'custom_field' => get_post_meta($product->get_id(), '_custom_field', true)
        ];
    }, $products);
}

🔹 What This Does:

Creates a new /wc/v3/custom-products endpoint.
Returns 10 published products with a custom meta field.

🔐 Method 2: Modify Existing API Responses

Add Custom Fields to Product Responses

add_filter('woocommerce_rest_prepare_product_object', 'add_custom_data_to_api_response', 10, 3);

function add_custom_data_to_api_response($response, $product, $request) {
    $response->data['custom_field'] = get_post_meta($product->get_id(), '_custom_field', true);
    return $response;
}

🔹 Usage:

Now, all /wc/v3/products responses include custom_field.

🔒 Method 3: Secure Custom Endpoints

Option A: WooCommerce API Keys (Recommended)

Go to WooCommerce → Settings → Advanced → REST API.
Click Add Key, generate Consumer Key & Secret.
Authenticate requests with:
curl –user “ck_xxx:cs_xxx” https://yoursite.com/wp-json/wc/v3/custom-products

Option B: JWT Authentication (For Mobile Apps)

Install JWT Authentication for WP REST API and modify permissions:

'permission_callback' => function() {
    return current_user_can('edit_products'); // Only admins/editors
}

⚡ Advanced Customizations

1. Create a POST Endpoint (Add Custom Data)

register_rest_route('wc/v3', '/submit-order', [
    'methods' => 'POST',
    'callback' => 'handle_custom_order_submission',
    'permission_callback' => '__return_true'
]);

function handle_custom_order_submission($request) {
    $params = $request->get_params();
    $order = wc_create_order();
    $order->add_product(wc_get_product($params['product_id']));
    $order->set_customer_id($params['user_id']);
    $order->save();
    return ['status' => 'success', 'order_id' => $order->get_id()];
}

2. Extend WC REST API Class (For Complex Logic)

class WC_Custom_API_Controller extends WC_REST_Controller {
    public function register_routes() {
        register_rest_route('wc/v3', '/custom-endpoint', [
            'methods' => 'GET',
            'callback' => [$this, 'get_custom_data'],
        ]);
    }
    public function get_custom_data() {
        return ['message' => 'Custom API Working!'];
    }
}
add_action('rest_api_init', function() { (new WC_Custom_API_Controller())->register_routes(); });

🔌 Testing Your API

Using Postman:
- Send a GET request to:
  https://yoursite.com/wp-json/wc/v3/custom-products
Via cURL:
curl -X GET https://yoursite.com/wp-json/wc/v3/custom-products

🚨 Common Issues & Fixes

Problem	Solution
403 Forbidden	Check API keys or JWT tokens
404 Not Found	Ensure permalinks are saved (`Settings → Permalinks → Save`)
Missing Data	Verify `register_rest_route` namespace matches (`wc/v3`)
Slow Responses	Optimize queries with `'posts_per_page'` limits

📚 Recommended Plugins

WP REST API Controller – Expose custom fields.
JWT Authentication – Secure endpoints.
ACF to REST API – Add ACF fields to responses.

🚀 Final Thoughts

Extending WooCommerce’s REST API lets you:
✔ Build mobile apps for your store
✔ Sync data with ERPs/CRMs
✔ Create custom checkout flows
✔ Automate order processing

Start with simple endpoints, then expand as needed. Always secure production APIs with authentication!

Which API extension will you build first? 🛒💻

November 30, 2025 7:11 AM