curl --request POST \
  --url https://openplatform.gateapi.io/v1/pay/convert/preview \
  --header 'Content-Type: application/json' \
  --header 'X-GatePay-Certificate-ClientId: <x-gatepay-certificate-clientid>' \
  --header 'X-GatePay-Nonce: <x-gatepay-nonce>' \
  --header 'X-GatePay-Signature: <x-gatepay-signature>' \
  --header 'X-GatePay-Timestamp: <x-gatepay-timestamp>' \
  --data '
{
  "buyCurrency": "USDT",
  "sellCurrency": "GT"
}
'

{
  "status": "SUCCESS",
  "code": "000000",
  "errorMessage": "",
  "data": {
    "sellCurrency": "GT",
    "buyCurrency": "USDT",
    "buyAmount": "1",
    "sellAmount": "0.04466796",
    "rate": "22.38741462",
    "quoteId": "PAY-16991c65"
  }
}