---
name: implement-flexpay
description: Implements Verotel FlexPay hosted order pages for purchases and subscriptions. Use when redirecting a buyer to FlexPay, verifying a FlexPay signature, or handling FlexPay postbacks.
title: FlexPay
summary: Hosted order page for a purchase or subscription. Sign the redirect, and answer every postback with OK.
slug: flexpay
order: 3
---

# Implement FlexPay

FlexPay sends the buyer to a hosted order page. Your server signs the redirect and handles postbacks. For iDEAL into a Yoursafe Business Account, follow the Yoursafe Direct skill instead. If this skill and a product page disagree, follow the product page.

## Read first

1. [FlexPay](/en/flexpay) — the purchase or subscription call, then postbacks, then signature calculation
2. [FlexPay plugins](/en/flexpay-plugins) when the store is WooCommerce or OpenCart

Use the official PHP or Java client when you can. The library builds the signature.

## Implement in this order

1. Take `shopID` and the FlexPay signature key from the Control Center website.
2. Choose the processor host for the brand: `secure.verotel.com`, `secure.billing.creditcard`, or `secure.gaycharge.com`.
3. Redirect the buyer with `GET /startorder`. `version` is `4`. `type` is `purchase` or `subscription`.
4. Publish a postback URL that validates the signature, records the sale, and answers.
5. Treat the browser return as a hint. The postback is the sale record.

## Credentials

- Shop ID (website ID) and FlexPay signature key from the Control Center.
- Merchant ID when the client library selects the brand from it.
- Postback URL saved on that website. A plugin install still needs the shop ID, signature key, and postback URL checked before go-live.

## Traps

- The signature is hex SHA-256 of a UTF-8 string. Start with the signature key, then the parameters in alphabetical order by name, joined as `:name=value`. Include an optional parameter only when it has a value.
- On `startorder`, leave `email` out of the signature, even when you send it.
- Postbacks arrive as GET. Verify the signature before you trust the fields.
- The postback response is HTTP 200 and the plain text `OK`, within 30 seconds. For card payments, a missing OK starts an automatic refund.
- `version` is `4`. A different version is part of the signed string, so the signature no longer matches.

## Done when

A signed `/startorder` opens the hosted page, a success postback verifies, and the handler returns `OK` with status 200.