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# Callbacks Guide

Use callback URLs to receive asynchronous payment and session updates.

## Overview

The public REST contract documents request-scoped callbacks:

* Payment callbacks through `PaymentRequestDto.callbackUrl`
* Checkout session callbacks through `settings.callbacks.paymentCallbackUrl`
* Tokenization session callbacks through `settings.callbacks.tokenizationCallbackUrl`

This documentation does not treat merchant-wide callback registration, shared callback secrets, or signature headers as part of the public API contract.

Use this guide only for request-scoped callbacks that you send as part of payments or sessions.

## Payment Callbacks

Send `callbackUrl` when creating a payment if your system needs an asynchronous notification.

The callback body is a `PaymentDto`.

```http
POST /v1/payments
Authorization: Basic {credentials}
Content-Type: application/json

{
  "merchantId": 12345,
  "referenceId": "order-1001",
  "invoiceNumber": "INV-1001",
  "amount": {
    "total": 10000,
    "currency": "UYU"
  },
  "paymentMethod": {
    "source": "card",
    "card": {
      "number": "4444333322221111",
      "expMonth": 12,
      "expYear": 2028,
      "cvc": "123",
      "cardholder": {
        "firstName": "Test",
        "lastName": "User",
        "email": "customer@example.com"
      }
    }
  },
  "capture": {
    "method": "automatic"
  },
  "callbackUrl": "https://merchant.example.com/callbacks/payments"
}
```

Use `GET /v1/payments/{paymentId}` if you need to confirm the canonical final resource state after receiving a callback.

## Checkout Session Callbacks

Use session callbacks when the customer is completing a hosted checkout flow.

The callback body is the same `PaymentDto` payload used by payment callbacks.

```http
POST /v1/sessions
Authorization: Basic {credentials}
Content-Type: application/json

{
  "merchantId": 12345,
  "referenceId": "checkout-session-1001",
  "type": "checkout",
  "paymentRequest": {
    "referenceId": "order-1001",
    "invoiceNumber": "INV-1001",
    "amount": {
      "total": 10000,
      "currency": "UYU"
    }
  },
  "settings": {
    "callbacks": {
      "paymentCallbackUrl": "https://merchant.example.com/callbacks/checkout"
    }
  }
}
```

## Tokenization Session Callbacks

Use a tokenization callback when the hosted flow is saving an instrument for later use.

The callback body is not a `PaymentDto`. Tokenization sessions use a tokenization-specific callback payload.

```http
POST /v1/sessions
Authorization: Basic {credentials}
Content-Type: application/json

{
  "merchantId": 12345,
  "referenceId": "tokenization-session-1001",
  "type": "tokenization",
  "customerId": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "settings": {
    "tokenization": {
      "type": "store"
    },
    "callbacks": {
      "tokenizationCallbackUrl": "https://merchant.example.com/callbacks/tokenization"
    }
  }
}
```

After receiving the callback, retrieve the current session or customer instruments if your application needs the latest persisted state.

{% hint style="info" %}
If you are tokenizing Google Pay or Apple Pay tokens with your own UI, you can use `POST /v1/tokenizations` instead of hosted sessions. The direct endpoint returns the token synchronously, so you do not need a callback URL. See the [Tokenization Guide](/rest-api/customers-and-saved-methods/tokenization-guide.md#direct-wallet-tokenization-google-pay--apple-pay) for details.
{% endhint %}

## Implementation Guidance

* Return a `2xx` response quickly from your callback endpoint
* Treat callbacks as asynchronous signals, then fetch the resource again if you need confirmation
* Make your callback handling idempotent, because retries can happen in distributed systems
* Keep callback URLs stable and HTTPS-only
* Do not expect a documented public signature header unless Plexo provides one for your specific integration

## Related Resources

* [Payment Processing](/rest-api/payments/payment-processing.md)
* [Tokenization Guide](/rest-api/customers-and-saved-methods/tokenization-guide.md)
* [SessionRequest](/rest-api/api-reference/models.md#sessionrequest)
* [PaymentRequestDto](/rest-api/api-reference/models.md#paymentrequestdto)


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