Step 1: Payment Methods

Retrieve available methods and saved payment options for your customer.

Endpoint

GET https://api.iimmpact.com/v2/payment-methods

Request headers

Field	Type	Required	Description
X-Api-Key	string	Yes	Your API key; keep it on your backend.
X-Timestamp	string	Yes	Current Unix time in seconds; within five minutes of server time.
X-Nonce	string	Yes	Fresh identifier for every request, including retries.
X-Signature	string	Yes	v1= followed by the request's HMAC signature.

Follow API Key Authentication. Sign an empty body and the sorted query.

Query fields

Field	Type	Required	Description
customer_external_id	string	Yes	Your own customer ID as a non-empty string. No UUID, numeric, or email format is required. Use the same value when creating a payment.

URL-encode the ID, including any +, &, or / characters. IDs are matched exactly within your account; an unknown ID returns no saved methods. Your backend must authorize the customer making the lookup.

Request example

curl 'https://api.iimmpact.com/v2/payment-methods?customer_external_id=CUS-1042' \
  --header "X-Api-Key: $API_KEY" \
  --header "X-Timestamp: $TIMESTAMP" \
  --header "X-Nonce: $NONCE" \
  --header "X-Signature: v1=$SIGNATURE"

Response fields

Field	Type	Description
data.payment_methods	array	Available methods. An empty array means payment is unavailable.
code	string	Method code for calculation and payment creation.
display_name	string	Checkout label.
icon_url	string or null	Always returned; null when no icon is available.
description	string or null	Always returned; null when no display text is available.
fee	object	Fixed or percentage payment fee.
saved_payment_methods	array	This customer's saved options for this method. Empty when none exist.

Saved payment method fields

Field	Type	Description
saved_payment_method_id	string	Opaque ID used to select this saved option at payment creation.
display_name	string	Ready-to-display label for the saved option.
card	object	Card display details for a saved card; omitted for other method types.
card.brand	string	Card brand, such as VISA, when card exists.
card.last4	string	Last four digits for display, when card exists.
card.expiry_month	integer	Expiry month, 1–12, when card exists.
card.expiry_year	integer	Four-digit expiry year, when card exists.

Use the parent method's code and the saved option's ID to pay. Card details are display-only; selection does not depend on them.

Response example — 200

{
  "data": {
    "payment_methods": [
      {
        "code": "CARD",
        "display_name": "Card",
        "icon_url": null,
        "description": null,
        "fee": {
          "type": "percentage",
          "value": "1.70"
        },
        "saved_payment_methods": [
          {
            "saved_payment_method_id": "spm_example",
            "display_name": "Visa ending in 1091",
            "card": {
              "brand": "VISA",
              "last4": "1091",
              "expiry_month": 12,
              "expiry_year": 2029
            }
          }
        ]
      },
      {
        "code": "FPX",
        "display_name": "FPX Online Banking",
        "icon_url": null,
        "description": "Pay with your bank account",
        "fee": {
          "type": "fixed",
          "value": "2.00"
        },
        "saved_payment_methods": []
      }
    ]
  }
}

Errors

HTTP	Code	Action
422	validation_error	customer_external_id is missing or empty. Supply your customer ID; its format is not checked.

See shared errors for authentication and service failures.

Next: Calculate Order.