Stop unsupported delivery orders before payment

The problem

Your customer fills their basket, reaches the checkout, and only then discovers you don't deliver to their postcode. The order is already placed, the payment provider has already run, and now you need to refund. This pattern wastes money and drives support tickets.

How Delivery Zone solves it

Call /v1/check server-side before the payment step runs. If canDeliver is false, block the order and return a clear reason code your UI can display to the customer. The customer gets an honest answer early — not a refund apology later.

Example API request

# Server-side: check whether a postcode can be delivered to
curl -X POST https://api.deliveryzone.fi/v1/check \
  -H "X-Api-Key: dz_live_..." \
  -H "Content-Type: application/json" \
  -d '{"destinationPostcode":"00100","basketValueCents":4500}'

# response
{
  "canDeliver": true,
  "zone": "Helsinki Center",
  "priceCents": 590,
  "reason": null
}

// Server-side only — never expose your API key in browser code
const res = await fetch('https://api.deliveryzone.fi/v1/check', {
  method: 'POST',
  headers: {
    'X-Api-Key': process.env.DZ_KEY,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ destinationPostcode: postcode, basketValueCents: basket }),
});
const data = await res.json();
if (!data.canDeliver) {
  showError(data.reason); // e.g. "OUT_OF_ZONE"
} else {
  setShippingFee(data.priceCents);
}

// PHP — server-side, keep API key out of frontend
$r = wp_remote_post('https://api.deliveryzone.fi/v1/check', [
  'headers' => [
    'X-Api-Key'    => get_option('dz_api_key'),
    'Content-Type' => 'application/json',
  ],
  'body' => json_encode([
    'destinationPostcode' => $postcode,
    'basketValueCents'    => $basketCents,
  ]),
]);
$data = json_decode(wp_remote_retrieve_body($r), true);
if (!$data['canDeliver']) return [];
foreach ($rates as $rate) {
  $rate->cost = $data['priceCents'] / 100;
}

Example customer-facing message

We don’t deliver to this postcode. Please check the postcode or choose a different delivery address. Your order has not been charged.

Who this is for

E-commerce shops

WooCommerce stores

Shopify stores

Custom checkout flows

Subscription boxes

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WooCommerce integration Custom checkout integration Example: block out-of-zone order