External payment gateways

How to manage payments and transactions via external services

Commerce Layer is integrated with some of the most popular payment gateways — Stripe, Adyen, Braintree, Paypal. They are all compliant with the PSD2 European regulation so that you can implement a payment flow that supports SCA and 3DS2.

Adding new payment gateways to our core is already provided for in our roadmap. Anyway, you already have the complete flexibility to connect whichever payment service provider you may need. To do that, just create an external payment gateway and define your custom endpoint(s) responding to the following transaction types:

  1. Authorization — to authorize a payment source

  2. Capture — to capture an authorization

  3. Void — to void an authorization

  4. Refund — to refund a capture, either totally or partially

Your external endpoint will be responsible for the actual integration with the payment gateway. The payment source associated with the order must be an external payment.

External gateways process payments synchronously by default. If you need your gateway to behave differently, check the asynchronous payments section.

Request

The request payload is a JSON:API compliant object you can query to perform your own computation. Aside from the target resource — which depends on the kind of gateway's transaction — some relationships are also included to avoid useless API roundtrips:

  • order

  • order.market

  • order.line_items

  • order.line_items.item

  • order.shipping_address

  • order.billing_address

{
"data": {
...
},
"included": [
{
"id": "wBXVhKzrnq",
"type": "orders",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
{
"id": "DvlGRmhdgX",
"type": "markets",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
{
"id": "kdPgtRXOKL",
"type": "line_items",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
{
"id": "XGZwpOSrWL",
"type": "skus",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
}
{
"id": "BgnguJvXmb",
"type": "addresses",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
{
"id": 'AlrkugwyVW',
"type": 'addresses',
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
{ ... }
]
}

Authorization

When you place an order, Commerce Layer triggers a POST request to the endpoint that you specified in the authorize_url field and creates an authorization.

Example

Payload
Response
Error
Payload

The request payload contains the external payment resource and includes the above-mentioned relationships:

{
"data": {
"id": "ZNKjeUYepv",
"type": "external_payments",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
"included": [
{ ... }
]
}
Response

The successful response must be a JSON object, returning a transaction token (e.g. the one provided by the payment gateway) and the total amount that has been authorized. If needed, you can add some metadata that will be copied into the authorization resource that is being created:

{
"success": true,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"metadata": {
"foo": "bar"
}
}
}
Error

On error, the response must be a JSON object containing a transaction token (e.g. the one provided by the payment gateway) and the authorization amount, along with an error code and an error message:

{
"success": false,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"error": {
"code": "YOUR-ERROR-CODE",
"message": "Your error message"
}
}
}

Capture

When you try to capture an authorization, Commerce Layer triggers a POST request to the endpoint that you specified in the capture_url field and creates a capture.

Example

Payload
Response
Error
Payload

The request payload contains the authorization resource and includes the above-mentioned relationships:

{
"data": {
"id": "yGzeUJxRJj",
"type": "authorizations",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
"included": [
{ ... }
]
}
Response

The successful response must be a JSON object, returning a transaction token (e.g. the one provided by the payment gateway) and the total amount that has been captured. If needed, you can add some metadata that will be copied into the capture resource that is being created:

{
"success": true,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"metadata": {
"foo": "bar"
}
}
}
Error

On error, the response must be a JSON object containing a transaction token (e.g. the one provided by the payment gateway) and the capture amount, along with an error code and an error message:

{
"success": false,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"error": {
"code": "YOUR-ERROR-CODE",
"message": "Your error message"
}
}
}

Void

When you try to void an authorization, Commerce Layer triggers a POST request to the endpoint that you specified in the void_url field and creates a void.

Example

Payload
Response
Error
Payload

The request payload contains the authorization resource and includes the above-mentioned relationships:

{
"data": {
"id": "yGzeUJxRJj",
"type": "authorizations",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
"included": [
{ ... }
]
}
Response

The successful response must be a JSON object, returning a transaction token (e.g. the one provided by the payment gateway) and the total amount that has been voided. If needed, you can add some metadata that will be copied into the void resource that is being created:

{
"success": true,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"metadata": {
"foo": "bar"
}
}
}
Error

On error, the response must be a JSON object containing a transaction token (e.g. the one provided by the payment gateway) and the void amount, along with an error code and an error message:

{
"success": false,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"error": {
"code": "YOUR-ERROR-CODE",
"message": "Your error message"
}
}
}

Refund

When you try to void a capture, Commerce Layer triggers a POST request to the endpoint that you specified in the refund_url field and creates a refund.

Example

Payload
Response
Error
Payload

The request payload contains the capture resource and includes the above-mentioned relationships:

{
"data": {
"id": "yJQDUVndWj",
"type": "captures",
"links": { ... },
"attributes": { ... },
"relationships": { ... },
"meta": { ... }
},
"included": [
{ ... }
]
}
Response

The successful response must be a JSON object, returning a transaction token (e.g. the one provided by the payment gateway) and the amount that has been refunded. If needed, you can add some metadata that will be copied into the refund resource that is being created:

{
"success": true,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 9900,
"metadata": {
"foo": "bar"
}
}
}
Error

On error, the response must be a JSON object containing a transaction token (e.g. the one provided by the payment gateway) and the refund amount, along with an error code and an error message:

{
"success": false,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 9900,
"error": {
"code": "YOUR-ERROR-CODE",
"message": "Your error message"
}
}
}

Asynchronous payments

It might be the case you don't want your gateway to process payments immediately. That's why Commerce Layer provides the option to mark your external gateway response as asynchronous and expose a webhook_endpoint_url you can call once the payment status changes.

Action ID

A payment is marked as asynchronous when the following conditions on the response to any of the external payment gateway transactions are met:

  • HTTP code is 202

  • It contains the action_id key, which uniquely identifies the related transaction

action_id uniqueness is mandatory for the webhook to detect the transaction later.

In this case, the external payment gateway creates the transaction setting the succeeded attribute to false, but considering it as pending. This way, the order can be placed without errors, but the order payment status doesn't change yet (even if the order is not editable anymore).

Example

Payload
Response
Error
Payload

The payload requested by the related transaction, as explained in the authorization, capture, void, and refund sections.

Response

The successful response must be a JSON object, returning a transaction token (e.g. the one provided by the payment gateway), the amount involved, and the unique identifier of the transaction. If needed, you can add some metadata that will be copied into the related transaction resource that is being created:

{
"success": true,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"action_id": "your-action-id"
"metadata": {
"foo": "bar"
}
}
}
Error

On error, the response must be a JSON object containing a transaction token (e.g. the one provided by the payment gateway) and the amount involved in the transaction, along with an error code and an error message:

{
"success": false,
"data": {
"transaction_token": "your-external-transaction-token",
"amount_cents": 12900,
"error": {
"code": "YOUR-ERROR-CODE",
"message": "Your error message"
}
}
}

Webhook endpoint

To notify the payment has changed its status, the external gateway exposes a webhook_endpoint_url you can call accordingly once the related payment transaction gets an update, as long as you follow these requirements:

  • It accepts only POST requests

  • You must include an X-CommerceLayer-Signature header, which contains the HMAC of the request payload signed with a SHA256 algorithm and the same shared secret already exposed by the external payment gateway

  • The request body must have the same structure as the response — a JSON object with the attributes you need to update the transaction with — and include the action_id previously used

The external payment gateway will use this data to fetch the pending transaction and update the attributes with the new values. On successful update, the transaction succeeded attribute is set to true and the order is updated to the right status — authorized, paid, voided, or refunded. On error, the order status remains as it is.

Updatable attributes

Only a subset of attributes is allowed for an update, assuming the main ones have already been set by the first async response (e.g. amount_cents and transaction_token cannot be updated). The updatable transaction fields are:

  • message

  • error_code

  • error_detail

  • avs_code

  • avs_message

  • cvv_code

  • cvv_message

  • fraud_review

Security

When you create a new external payment gateway, a shared secret is generated. We recommend verifying the callback authenticity by signing the payload with that shared secret and comparing the result with the callback signature header.