Callbacks

When a pay-in is received, or a payout finishes (success or refused), the platform sends a POST request to your callback URL.

Callback URL

Order	URL used
Pay-in	callbackUrl passed when creating the order; otherwise the pay-in callback URL in the merchant console
Payout	callbackUrl passed when creating the order; otherwise the payout callback URL in the merchant console

The URL must be a publicly reachable https address. Only payouts created through the OpenAPI get callbacks; payouts submitted manually in the merchant console don't.

Request

POST /your/callback/path HTTP/1.1
Content-Type: application/json

{"encryptedData":"Base64 string"}

encryptedData is JSON encrypted with your public key (PKCS#1 v1.5). Decrypt it with your private key.

Pay-in callback

{
  "OrderNo": "PI1845290017342758912",
  "MerchantNo": "your merchant number",
  "MerchantOrderNo": "A20261013001",
  "PayTime": "2026-10-13T12:00:00",
  "OrderState": 6,
  "Quantity": 13.7,
  "FiatCurrency": 100.0
}

Field	Type	Description
OrderNo	string	Platform order number
MerchantNo	string	Merchant number
MerchantOrderNo	string	Your merchant order number
PayTime	string	When the customer paid, UTC+8, yyyy-MM-ddTHH:mm:ss
OrderState	int	Always 6 (Released: the platform has confirmed the money and credited the USDT to your balance)
Quantity	number	USDT amount of the order (before fees)
FiatCurrency	number	Fiat amount (the order amount)

Payout callback

{
  "OrderNo": "PO1845290017342758913",
  "MerchantNo": "your merchant number",
  "MerchantOrderNo": "PO20261013001",
  "PayTime": "2026-10-13T12:30:00",
  "state": 4
}

Field	Type	Description
OrderNo	string	Platform payout number
MerchantNo	string	Merchant number
MerchantOrderNo	string	Your merchant order number
PayTime	string | null	When it finished, UTC+8
state	int	4 succeeded; 5 refused (the frozen USDT has been refunded)

Field name casing

Callback fields start with a capital letter (OrderNo), while the payout state is lowercase state — unlike the camelCase API responses. Parse field names case-insensitively. Numbers in callbacks are not rounded; Get order is the source of truth.

What to reply

After processing, reply with HTTP 2xx and a body of either:

• plain text success (or ok, case-insensitive, no surrounding spaces or newlines), or
• JSON {"code":200}

Anything else (timeouts, non-2xx, other content) counts as a failure and the platform will retry.

Retries

The first callback is sent within 30 seconds after the order completes. Failed callbacks are retried at these intervals, at most 5 attempts in total:

Attempt	After the previous one
1	within 30 seconds of completion
2	3 minutes
3	9 minutes
4	27 minutes
5	81 minutes

After 5 failures the platform stops. You can still see the order in the merchant console or with Get order. A failed callback does not mean the payment failed.

Required checks

Callbacks are not signed

Callbacks are only encrypted with your public key — they are not signed. Anyone who has your public key can forge a "paid" callback, so never credit a customer based on the callback content alone.

Handle each callback in this order (the sample code does all of this):

1. Decrypt it; if that fails, reply with a failure.
2. Check the merchant number is yours.
3. Deduplicate: process the same OrderNo + state only once. The platform retries, and your own processing may be interrupted before you reply success. Put a unique index on "platform order number + state" and record it in the same database transaction as the crediting.
4. Verify with Get order using MerchantOrderNo, and trust its result:
   • pay-in: the state must be 6 (Released) or 3 (Success), and the amount must equal the callback's FiatCurrency and the amount of the order in your own system;
   • payout: the state must equal the callback's state, and the amount must equal the payout amount in your own system.
5. Only then credit / update your order, and finally reply success.

Also limit the request body size (a few KB is enough), accept POST only, and don't log full request bodies.