curl --request GET \
  --url https://api.xpaycheckout.com/customer/{customerId} \
  --header 'Authorization: Basic <encoded-value>'

{
  "customerId": "cus_Tfd3Jq1tZxPjYVhRQW2r3",
  "customerDetails": {
    "name": "John Doe",
    "email": "john.doe@example.com",
    "contactNumber": "+919123456789",
    "customerAddress": {
      "country": "US",
      "postalCode": "2424"
    }
  }
}