Verifying payments

Your page can be edited by its user. A resolved pay() promise only tells your UI what happened; it doesn’t prove anything to your server.

The flow

Your page asks

Your page calls pay, request or createLink with a reference, such as your order ID.

Zend records it

Zend records the payment from its own records. For pay, it checks the payer, recipient and amount against what your app asked for.

Zend tells your server

Zend sends a signed payment.completed (or link.claimed) webhook with your reference.

Your server credits

Your server verifies the signature, dedupes on the event id, and credits the order.

import { verifyWebhook } from "@zendfi/appkit/server";

app.post("/zend/webhook", express.text({ type: "*/*" }), async (req, res) => {
  if (!verifyWebhook(req.body, req.header("x-zend-signature") ?? "", process.env.ZEND_WEBHOOK_SECRET!)) {
    return res.sendStatus(401);
  }
  const event = JSON.parse(req.body);
  if (await alreadyHandled(event.id)) return res.sendStatus(200);

  if (event.type === "payment.completed") {
    await creditOrder(event.data.reference, event.data.amount_usd, event.data.from);
  }
  res.sendStatus(200);
});

Look up a payment

If you need to check a reference directly, for example when a user says they paid:

curl "https://api.usezend.app/api/zend/v2/apps/server/payments?reference=article_7" \
  -H "Authorization: Bearer $ZEND_APP_KEY"

{
  "payments": [
    {
      "payment_id": "…",
      "from": "zu_...",
      "to": "zu_...",
      "amount_usd": 1.32,
      "reference": "article_7",
      "created_at": "2026-11-02T10:00:00Z"
    }
  ]
}

Returns up to 50 payments for that reference, newest first.

Catching up after downtime

Deliveries retry for about a day. If your server was down longer, GET /apps/server/events returns the last 100 events with delivered_at. See Webhooks.

Get started

Build a ZApp

Money

Fair results

Ship

Examples

The flow

Look up a payment

Catching up after downtime

​The flow

​Look up a payment

​Catching up after downtime

The flow

Look up a payment

Catching up after downtime