Authorization Updates

Simulate authorization updates on existing transactions, such as when a merchant adjusts the amount before settlement.

Beta Feature

The Transaction Simulations feature is currently in beta. API endpoints and behavior may change as we continue to refine the product. Simulation endpoints are available in development environments only — production returns 404 Not Found.

Simulate an authorization update on an existing transaction — for example, when a merchant adjusts the amount before settlement. This simulates an ISO 0120 authorization update message.

Use this to test how your integration handles authorization amount changes, such as a restaurant adding a tip or a gas station adjusting the final pump amount.

Endpoint

PATCH /v1/simulate/transactions/:transactionId/authorize

Path parameters

Parameter	Type	Required	Description
transactionId	string (UUID)	Yes	The ID of an existing transaction to update.

Headers

Header	Type	Required	Description
Api-Key	string	Yes	Your tenant API key. The tenant scope is resolved from this key.
Content-Type	application/json	Yes	—

Body

Field	Type	Required	Description
amount	integer	Yes	The new transaction amount in cents (merchant currency). Must be a positive integer.

Example request

{
  "amount": 6000
}

Response

A successful response returns the transaction ID and status.

200 OK

{
  "transactionId": "f3a1c92e-1b3d-4d1e-bb22-12c0a4d5b8f9",
  "status": "authorized"
}

Field	Type	Description
transactionId	string (UUID)	The transaction ID.
status	string	The transaction status: authorized.

Errors

Status	When
400 Bad Request	Invalid body (missing or negative amount), transaction already settled or closed, no card associated with the transaction, or the card has no processor ID.
404 Not Found	Endpoint not available in production, simulations are not enabled for your tenant, or the transaction does not exist.
500 Internal Server Error	Invalid currency or unhandled error during simulation.

Behavior notes

• Transaction must be open. You can only update authorizations that have not yet settled or closed.
• FX conversion applies. The new amount is converted using the transaction’s original merchant and billing currencies.
• Triggers webhooks. The update fires the same authorization update webhooks as a real update.

Example

curl -X PATCH https://api-dev.rain.xyz/v1/simulate/transactions/f3a1c92e-1b3d-4d1e-bb22-12c0a4d5b8f9/authorize \
  -H "Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 6000
  }'