WooCommerce Payment Gateway Development

Before writing code

Fetch live docs:

1. Web-search site:developer.woocommerce.com payment gateway api for payment gateway guide
2. Web-search woocommerce payment gateway tutorial for implementation patterns
3. Fetch https://woocommerce.github.io/code-reference/classes/WC-Payment-Gateway.html for class reference

Gateway Architecture

Base Class: WC_Payment_Gateway

All gateways extend WC_Payment_Gateway (which extends WC_Settings_API):

Registration

Filter woocommerce_payment_gateways:

add_filter( 'woocommerce_payment_gateways', function( $gateways ) {
    $gateways[] = 'My_Payment_Gateway';
    return $gateways;
});

Implementation Methods

Required Methods

• __construct() — set $id, $method_title, $supports, call init_form_fields(), init_settings(), load saved settings, register process_admin_options hook
• init_form_fields() — define admin settings (API keys, sandbox mode, etc.)
• process_payment( $order_id ) — core payment logic, returns result + redirect array

Optional Methods

• payment_fields() — render custom payment form HTML on checkout
• validate_fields() — validate payment form input
• process_refund( $order_id, $amount, $reason ) — handle refunds
• get_icon() — customize the gateway icon display

process_payment Return Format

return [
    'result'   => 'success', // or 'failure'
    'redirect' => $order->get_checkout_order_received_url(),
];

Integration Models

Direct Integration

Gateway processes payment inline:

1. Collect card data via payment_fields() (or tokenized via JS SDK)
2. Call payment processor API in process_payment()
3. Mark order: $order->payment_complete( $transaction_id )
4. Return success with redirect to thank-you page

Redirect Integration

Customer redirected to external payment page:

1. process_payment() returns redirect URL to processor
2. Processor handles payment and redirects back
3. Handle return via a webhook or callback URL
4. Process the response and update order status

Hosted/Iframe Integration

Payment form loaded in iframe on checkout page:

• Set $has_fields = true
• Render iframe/JS SDK in payment_fields()
• Handle tokenization callback

Supports Array

$this->supports = [
    'products',           // Basic payment support
    'refunds',            // process_refund()
    'tokenization',       // Saved payment methods
    'subscriptions',      // WooCommerce Subscriptions
    'subscription_cancellation',
    'subscription_reactivation',
    'subscription_suspension',
    'subscription_amount_changes',
    'subscription_date_changes',
];

Tokenization (Saved Payment Methods)

WC_Payment_Token System

• Extend WC_Payment_Token_CC (credit cards) or WC_Payment_Token (generic)
• $this->supports[] = 'tokenization'
• Override tokenization_script() to enqueue JS
• Save tokens via WC_Payment_Tokens::set_users_default()
• Customer manages saved methods in My Account > Payment Methods

Webhook/IPN Handling

Registering Webhook Endpoints

Use WC_API to register callback URLs:

• add_action( 'woocommerce_api_{$id}', [ $this, 'handle_webhook' ] )
• Callback URL: home_url( '/wc-api/{$id}/' )
• Verify signatures, process payment notifications, update order status

Order Status Management

• $order->update_status( 'processing', 'Payment received' ) — status + note
• $order->payment_complete( $transaction_id ) — marks paid, triggers emails
• $order->update_status( 'failed', 'Payment failed' ) — mark failed
• $order->add_order_note( 'Note text' ) — add admin/customer note

Block Checkout Support

For block-based checkout, gateways need a JS integration:

1. Register a payment method via @woocommerce/blocks-registry → registerPaymentMethod()
2. Provide React components for: content, edit, label
3. Define canMakePayment callback
4. Handle payment data submission via onPaymentSetup event

Best Practices

• Never log or store raw credit card data
• Always use sandbox/test mode for development
• Verify webhook signatures to prevent spoofing
• Handle all error states gracefully with clear customer messages
• Support refunds if the processor allows them
• Declare cart_checkout_blocks compatibility and provide block checkout integration
• Use $order->payment_complete() — it handles status, stock reduction, and email triggers
• Store transaction IDs via $order->set_transaction_id()

Fetch the WooCommerce payment gateway documentation and code reference for exact method signatures, supported features, and block checkout integration patterns before implementing.