Starex Pay

Starex Pay is a payment page. You redirect the customer to it with an order number and an amount, and they pick a payment method and pay. Starex Pay handles everything related to payment systems — all you have to do is build one link and implement two endpoints.

1. Overview

PAY_URL and SECRET_KEY are issued by Starex; you give Starex your prepare and complete URLs.

Item	Description
`PAY_URL`	Base URL of the payment page
`SECRET_KEY`	Secret key for signatures — used only on the server side
`prepare` URL	Order validation endpoint
`complete` URL	Payment confirmation endpoint

2. How it works

requests in green go to your endpoints; everything else is handled by Starex Pay.

3. Payment link

GET {PAY_URL}/checkout

Parameter	Type	Description
`order_id`	string	Order number in your system
`amount`	integer	Payment amount (in tiyin)
`sign`	string	Verification string (SHA-256): `sha256(order_id + amount + SECRET_KEY)`

From this link the customer picks a payment method, pays in the payment system and returns to the result page.

Building the link

$sign = hash('sha256', $orderId . $amount . $secretKey);

$link = $payUrl . '/checkout?' . http_build_query([
    'order_id' => $orderId,
    'amount'   => $amount,
    'sign'     => $sign,
]);

header('Location: ' . $link);

const sign = crypto.createHash('sha256')
  .update(`${orderId}${amount}${secretKey}`).digest('hex');

const link = `${payUrl}/checkout?` + new URLSearchParams({
  order_id: orderId, amount: String(amount), sign,
});

res.redirect(link);

sign = hashlib.sha256(f"{order_id}{amount}{secret_key}".encode()).hexdigest()

link = f"{pay_url}/checkout?" + urlencode({
    "order_id": order_id, "amount": amount, "sign": sign,
})

Use a unique order_id for every payment.
A link is valid for 24 hours — generate a new one afterwards.
A paid order cannot be paid again — the customer is shown the payment status.

4. Requests

Both requests are sent with POST and a JSON body. The response must return HTTP 200 within 10 seconds.

Prepare

POST {YOUR_PREPARE_URL}

{
  "ext_trans_id": 1042,
  "ext_payment_id": 3311,
  "order_id": "A-10245",
  "amount": 4500000,
  "action": 0,
  "sign_time": "2026-07-28 14:05:21",
  "sign_string": "9c2f...b81d"
}

Field	Type	Description
`ext_trans_id`	integer	Payment number in the Starex Pay system
`ext_payment_id`	integer	Transaction number in the Starex Pay system
`order_id`	string	Order number in your system
`amount`	integer	Payment amount (in tiyin)
`action`	integer	Action being performed. `0` — Prepare
`sign_time`	string	Request time. Format `YYYY-MM-DD HH:MM:SS`
`sign_string`	string	Verification string (SHA-256): `sha256(ext_trans_id + SECRET_KEY + order_id + amount + action + sign_time)`

Response

{
  "error": 0,
  "error_note": "OK",
  "prepare_id": "778812"
}

Field	Type	Description
`error`	integer	Operation result. `0` — success
`error_note`	string	Result description
`prepare_id`	string	Payment identifier in your system

Complete

POST {YOUR_COMPLETE_URL}

{
  "ext_trans_id": 1042,
  "ext_payment_id": 3311,
  "order_id": "A-10245",
  "prepare_id": "778812",
  "amount": 4500000,
  "action": 1,
  "sign_time": "2026-07-28 14:07:03",
  "sign_string": "1ae4...7c02"
}

Field	Type	Description
`ext_trans_id`	integer	Payment number in the Starex Pay system
`ext_payment_id`	integer	Transaction number in the Starex Pay system
`order_id`	string	Order number in your system
`prepare_id`	string	Payment identifier in your system, returned in the response to the `prepare` request
`amount`	integer	Payment amount (in tiyin)
`action`	integer	Action being performed. `1` — Complete
`sign_time`	string	Request time. Format `YYYY-MM-DD HH:MM:SS`
`sign_string`	string	Verification string (SHA-256): `sha256(ext_trans_id + SECRET_KEY + order_id + prepare_id + amount + action + sign_time)`

Response

{
  "error": 0,
  "error_note": "OK",
  "confirm_id": "990145"
}

Field	Type	Description
`error`	integer	Operation result. `0` — success
`error_note`	string	Result description
`confirm_id`	string	Confirmation identifier in your system

An error returned in the complete response marks the payment as failed.

5. Returned error codes

Code	Message shown to the customer	When to return it
`0`	Operation completed successfully	Everything is fine
`-1`	Payment verification failed	`sign_string` did not match
`-2`	Payment amount is incorrect	`amount` does not equal the order amount
`-3`	Requested operation is not available	Unknown `action` value
`-4`	This order has already been paid	Repeated payment attempt
`-5`	Order not found	No order for this `order_id`
`-6`	Transaction not found	No payment for this `prepare_id`
`-7`	Failed to update the order, please try again	Internal failure
`-8`	Invalid payment request	A required field is missing
`-9`	This transaction has already been cancelled	Attempt to continue a cancelled payment

A code that is not in this list is treated as a failed payment.