Guides

WooCommerce and PrestaShop as API clients

The WooCommerce plugin uses the same public API you do. For PrestaShop we show how to connect a store directly.

WooCommerce: the KSeF Faktury plugin

The "KSeF Faktury for WooCommerce" plugin is an ordinary client of this API. It passed tests on KSeF TEST (classic and block checkout, refunds, HPOS); it will be listed on WordPress.org after launch, and early access participants get it sooner.

A "I want a VAT invoice" box and a NIP field with a checksum check in classic and block checkout. It can also read the NIP from an existing field (e.g. _billing_nip, vat_number).
Once an order with a NIP is paid, it sends it in the background (Action Scheduler) with an Idempotency-Key and retries on network errors, 429 and 5xx. Cash on delivery is sent on completion.
A WooCommerce refund becomes a correction.
The order screen shows the status, invoice and KSeF numbers and PDF links; the buyer sees the PDF on the order page.
Only orders with a NIP leave the store, with only the data needed: no IP address, user agent, phone or customer id.
Requirements: PHP 7.4+, WooCommerce 8.9+, HPOS compatible.

The plugin sends the order in the WooCommerce REST API v3 format as it is. You can do the same in your own code:

POST /v1/invoices

curl -X POST https://app.ksefshop.pl/v1/invoices \
  -H "Authorization: Bearer $KSEF_API_KEY" \
  -H "Idempotency-Key: woo-order-727" \
  -H "Content-Type: application/json" \
  -d '{
  "woocommerce_order": {
    "id": 727,
    "number": "727",
    "status": "processing",
    "currency": "PLN",
    "date_created_gmt": "2026-10-19T09:12:40",
    "date_paid_gmt": "2026-10-19T09:13:05",
    "billing": {
      "first_name": "Jan",
      "last_name": "Kowalski",
      "company": "Testowa Firma sp. z o.o.",
      "address_1": "ul. Prosta 20",
      "city": "Warszawa",
      "postcode": "00-850",
      "country": "PL",
      "email": "jan@example.com"
    },
    "payment_method": "cod",
    "meta_data": [
      {
        "key": "_ksef_buyer_nip",
        "value": "5260250274"
      }
    ],
    "line_items": [
      {
        "id": 41,
        "name": "Kubek ceramiczny 350 ml",
        "quantity": 2,
        "subtotal": "79.67",
        "subtotal_tax": "18.33",
        "total": "79.67",
        "total_tax": "18.33",
        "taxes": [
          {
            "id": 1,
            "total": "18.33"
          }
        ]
      }
    ],
    "tax_lines": [
      {
        "id": 51,
        "rate_id": 1,
        "rate_percent": 23
      }
    ],
    "shipping_lines": []
  }
}'

<?php
$payload = [
    'woocommerce_order' => [
        'id' => 727,
        'number' => '727',
        'status' => 'processing',
        'currency' => 'PLN',
        'date_created_gmt' => '2026-10-19T09:12:40',
        'date_paid_gmt' => '2026-10-19T09:13:05',
        'billing' => [
            'first_name' => 'Jan',
            'last_name' => 'Kowalski',
            'company' => 'Testowa Firma sp. z o.o.',
            'address_1' => 'ul. Prosta 20',
            'city' => 'Warszawa',
            'postcode' => '00-850',
            'country' => 'PL',
            'email' => 'jan@example.com',
        ],
        'payment_method' => 'cod',
        'meta_data' => [
            ['key' => '_ksef_buyer_nip', 'value' => '5260250274'],
        ],
        'line_items' => [
            [
                'id' => 41,
                'name' => 'Kubek ceramiczny 350 ml',
                'quantity' => 2,
                'subtotal' => '79.67',
                'subtotal_tax' => '18.33',
                'total' => '79.67',
                'total_tax' => '18.33',
                'taxes' => [
                    ['id' => 1, 'total' => '18.33'],
                ],
            ],
        ],
        'tax_lines' => [
            ['id' => 51, 'rate_id' => 1, 'rate_percent' => 23],
        ],
        'shipping_lines' => [],
    ],
];

$ch = curl_init('https://app.ksefshop.pl/v1/invoices');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer ' . getenv('KSEF_API_KEY'),
        'Idempotency-Key: woo-order-727',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode($payload, JSON_UNESCAPED_UNICODE),
]);
$body = curl_exec($ch);
$status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
curl_close($ch);

$data = json_decode($body, true);
if ($status >= 400) {
    throw new RuntimeException($data['error']['code'] . ': ' . $data['error']['message']);
}
echo var_export($data['id'], true), ' ', var_export($data['status'], true), PHP_EOL;

const res = await fetch("https://app.ksefshop.pl/v1/invoices", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.KSEF_API_KEY}`,
    "Idempotency-Key": "woo-order-727",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    woocommerce_order: {
      id: 727,
      number: "727",
      status: "processing",
      currency: "PLN",
      date_created_gmt: "2026-10-19T09:12:40",
      date_paid_gmt: "2026-10-19T09:13:05",
      billing: {
        first_name: "Jan",
        last_name: "Kowalski",
        company: "Testowa Firma sp. z o.o.",
        address_1: "ul. Prosta 20",
        city: "Warszawa",
        postcode: "00-850",
        country: "PL",
        email: "jan@example.com",
      },
      payment_method: "cod",
      meta_data: [
        { key: "_ksef_buyer_nip", value: "5260250274" },
      ],
      line_items: [
        {
          id: 41,
          name: "Kubek ceramiczny 350 ml",
          quantity: 2,
          subtotal: "79.67",
          subtotal_tax: "18.33",
          total: "79.67",
          total_tax: "18.33",
          taxes: [
            { id: 1, total: "18.33" },
          ],
        },
      ],
      tax_lines: [
        { id: 51, rate_id: 1, rate_percent: 23 },
      ],
      shipping_lines: [],
    },
  }),
});
const data = await res.json();
if (!res.ok) throw new Error(`${data.error.code}: ${data.error.message}`);
console.log(data.id, data.status);

import os
import requests

resp = requests.post(
    "https://app.ksefshop.pl/v1/invoices",
    headers={
        "Authorization": f"Bearer {os.environ['KSEF_API_KEY']}",
        "Idempotency-Key": "woo-order-727",
    },
    json={
        "woocommerce_order": {
            "id": 727,
            "number": "727",
            "status": "processing",
            "currency": "PLN",
            "date_created_gmt": "2026-10-19T09:12:40",
            "date_paid_gmt": "2026-10-19T09:13:05",
            "billing": {
                "first_name": "Jan",
                "last_name": "Kowalski",
                "company": "Testowa Firma sp. z o.o.",
                "address_1": "ul. Prosta 20",
                "city": "Warszawa",
                "postcode": "00-850",
                "country": "PL",
                "email": "jan@example.com",
            },
            "payment_method": "cod",
            "meta_data": [
                {"key": "_ksef_buyer_nip", "value": "5260250274"},
            ],
            "line_items": [
                {
                    "id": 41,
                    "name": "Kubek ceramiczny 350 ml",
                    "quantity": 2,
                    "subtotal": "79.67",
                    "subtotal_tax": "18.33",
                    "total": "79.67",
                    "total_tax": "18.33",
                    "taxes": [
                        {"id": 1, "total": "18.33"},
                    ],
                },
            ],
            "tax_lines": [
                {"id": 51, "rate_id": 1, "rate_percent": 23},
            ],
            "shipping_lines": [],
        },
    },
    timeout=30,
)
data = resp.json()
if not resp.ok:
    raise RuntimeError(f"{data['error']['code']}: {data['error']['message']}")
print(data["id"], data["status"])

We read the NIP from meta_data: _ksef_buyer_nip (the plugin's field), the block checkout field, _billing_nip or vat_number. The VAT rate comes from tax_lines.rate_percent.

PrestaShop: directly through the API

There is no ready PrestaShop module yet. Until then a PrestaShop store connects to the API directly: once payment is confirmed (the actionPaymentConfirmation hook) it sends the order in the neutral format. Below is a module sketch for your developer to finish.

PrestaShop module sketch

<?php
// modules/ksefapi/ksefapi.php - sketch: paid orders with a NIP -> POST /v1/invoices
class KsefApi extends Module
{
    public function __construct()
    {
        $this->name = 'ksefapi';
        $this->version = '0.1.0';
        $this->author = 'Your company';
        parent::__construct();
        $this->displayName = 'KSeF Faktury API';
    }

    public function install()
    {
        return parent::install() && $this->registerHook('actionPaymentConfirmation');
    }

    public function hookActionPaymentConfirmation(array $params)
    {
        $order = new Order((int) $params['id_order']);
        $address = new Address((int) $order->id_address_invoice);
        if (trim((string) $address->vat_number) === '') {
            return; // consumer without a NIP: no KSeF invoice
        }
        $lines = [];
        foreach ($order->getProducts() as $p) {
            $lines[] = [
                'name' => $p['product_name'],
                'sku' => $p['product_reference'],
                'quantity' => (int) $p['product_quantity'],
                'unit_price' => number_format((float) $p['unit_price_tax_incl'], 2, '.', ''),
                'vat_rate' => (string) (int) round((float) $p['tax_rate']),
            ];
        }
        $shipping = [];
        if ((float) $order->total_shipping_tax_incl > 0) {
            $shipping[] = [
                'name' => (new Carrier((int) $order->id_carrier))->name,
                'price' => number_format((float) $order->total_shipping_tax_incl, 2, '.', ''),
                'vat_rate' => (string) (int) round((float) $order->carrier_tax_rate),
            ];
        }
        $payload = ['order' => [
            'external_id' => 'PS-' . $order->id,
            'number' => $order->reference,
            'paid_at' => gmdate('c'),
            'currency' => (new Currency((int) $order->id_currency))->iso_code,
            'buyer' => [
                'nip' => $address->vat_number,
                'name' => $address->company ?: trim($address->firstname . ' ' . $address->lastname),
                'address_line1' => $address->address1,
                'address_line2' => trim($address->postcode . ' ' . $address->city),
                'email' => (new Customer((int) $order->id_customer))->email,
            ],
            'lines' => $lines,
            'shipping' => $shipping,
        ]];

        // In production send from a queue or cron and retry with the same key.
        $ch = curl_init('https://app.ksefshop.pl/v1/invoices');
        curl_setopt_array($ch, [
            CURLOPT_CUSTOMREQUEST => 'POST',
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT => 30,
            CURLOPT_HTTPHEADER => [
                'Authorization: Bearer ' . Configuration::get('KSEFAPI_KEY'),
                'Idempotency-Key: order-PS-' . $order->id,
                'Content-Type: application/json',
            ],
            CURLOPT_POSTFIELDS => json_encode($payload, JSON_UNESCAPED_UNICODE),
        ]);
        $invoice = json_decode((string) curl_exec($ch), true);
        curl_close($ch);
        if (isset($invoice['id'])) {
            Configuration::updateValue('KSEFAPI_INV_' . $order->id, $invoice['id']);
        }
    }
}

Before production:

Send from a queue or cron with retries rather than during the payment. Pattern: idempotency.
Spread cart rules over the lines as discount.
Send refunds (e.g. the actionOrderSlipAdd hook) to POST /v1/invoices/{id}/corrections. Corrections
Store the KSeF number and pdf_url on the order after the invoice.accepted event. Webhooks

Other systems

The API takes an order from any system that knows the order is paid: your own store, an ERP or a marketplace integration. A Shopify store does not need the API: the KSeF Faktury app is enough.

WooCommerce and PrestaShop as API clients

WooCommerce: the KSeF Faktury plugin

PrestaShop: directly through the API

Other systems

API early access

Thank you!