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PayFlow API Overview

This section documents the PayFlow REST API. Use it to process payments, issue refunds, manage customers, and retrieve transaction history. For the current version and base URL, see the API Reference.

Who is this for?

This reference is written for back-end developers integrating PayFlow into a web or mobile application. You should be comfortable with REST APIs and HTTP request/response patterns.

What you can do​

FeatureDescription
PaymentsCharge a customer and retrieve a payment by ID.
RefundsIssue full or partial refunds against a payment.
CustomersCreate and list customer records to charge against.
Transaction historyList payments to reconcile and report.
Safe retriesSend an Idempotency-Key on writes so a retry can't create a duplicate.

API design​

The PayFlow API follows REST conventions:

  • All requests use HTTPS
  • Request and response bodies use JSON
  • Standard HTTP status codes indicate success or failure
  • All timestamps are returned in ISO 8601 format (2026-03-18T09:00:00Z)
  • Monetary values are expressed in minor currency units (for example, pence for GBP, cents for USD)

Quick example​

This request creates a £25.00 payment for an existing customer. You need a test key, which makes no real charges (Authentication), and a customer ID (Create a customer). Replace YOUR_TEST_KEY and cus_9KZFXWr with your own values. The amount is in pence, so 2500 is £25.00.

The Idempotency-Key header makes the request safe to retry: sending the same key again returns the original response instead of creating a second charge.

curl https://api.payflow.io/v2/payments \
  -H "Authorization: Bearer YOUR_TEST_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: f47ac10b-58cc-4372-a567-0e02b2c3d479" \
  -d '{
    "amount": 2500,
    "currency": "gbp",
    "customer_id": "cus_9KZFXWr",
    "description": "Q1 invoice"
  }'

Response:

{
  "id": "pay_8xKq9mNw",
  "object": "payment",
  "status": "succeeded",
  "amount": 2500,
  "currency": "gbp",
  "created": "2026-03-18T09:00:00Z"
}

A status of succeeded means the payment went through. Keep the id to look up or refund the payment later.

Next steps​

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