Building a WooCommerce Plugin for Paychainly: Accept Crypto Payments in Your Store

Prerequisites

You need a WordPress + WooCommerce installation, a Paychainly account with an API key, and a webhook endpoint accessible from the internet (use ngrok for local development).

Plugin Structure

woocommerce-paychainly/
├── woocommerce-paychainly.php   # Main plugin file
├── includes/
│   ├── class-paychainly-gateway.php
│   └── class-webhook-handler.php

Registering the Gateway

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

Processing the Payment

When a customer clicks "Place Order", your gateway calls Paychainly to create a deposit session and redirects the customer to a payment page showing the USDT deposit address and a countdown timer:

public function process_payment($order_id) {
    $order = wc_get_order($order_id);
    $amount = $order->get_total();

    $response = wp_remote_post('https://paychainly.com/api/v1/addresses/start-session', [
        'headers' => ['x-api-key' => $this->api_key, 'Content-Type' => 'application/json'],
        'body' => json_encode(['userId' => (string)$order_id, 'amount' => $amount]),
    ]);

    $data = json_decode(wp_remote_retrieve_body($response), true);
    $order->update_meta_data('_paychainly_address', $data['address']);
    $order->save();

    return ['result' => 'success', 'redirect' => $this->get_return_url($order)];
}

Handling the Webhook

Register a WooCommerce API endpoint to receive the deposit_detected webhook. Verify the signature, then mark the order as paid:

$order->payment_complete($payload['txHash']);
$order->add_order_note('Paychainly: payment confirmed — ' . $payload['txHash']);

Testing

Enable sandbox mode in Paychainly, use the POST /api/sandbox/credit endpoint to simulate a deposit, and verify your webhook handler marks the order paid correctly.