The API specification: docs.connect.squareup.com/api/connect/v2#endpoint-createcustomercard
{
"billing_address": {
"address_line_1": "78B Avenue Marceau",
"address_line_2": "",
"address_line_3": "",
"administrative_district_level_1": "Paris",
"administrative_district_level_2": "",
"administrative_district_level_3": "",
"country": "FR",
"locality": "Paris",
"postal_code": "75008",
"sublocality": "",
"sublocality_2": "",
"sublocality_3": ""
},
"card_brand": "VISA",
"cardholder_name": "DMITRY FEDYUK",
"exp_month": 7,
"exp_year": 2021,
"id": "82e66bb3-36ab-51cd-45e7-f9f251c73b08",
"last_4": "5858"
}