The API specification: docs.connect.squareup.com/api/connect/v2#endpoint-createcustomer
{
"customer": {
"address": {
"address_line_1": "500 Electric Ave",
"address_line_2": "Suite 600",
"locality": "New York",
"administrative_district_level_1": "NY",
"postal_code": "10003",
"country": "US"
},
"created_at": "2016-03-23T20:21:54.859Z",
"email_address": "Amelia.Earhart@example.com",
"family_name": "Earhart",
"given_name": "Amelia",
"id": "JDKYHBWT1D4F8MFH63DBMEN8Y4",
"note": "a customer",
"phone_number": "1-212-555-4240",
"reference_id": "YOUR_REFERENCE_ID",
"updated_at": "2016-03-23T20:21:54.859Z"
}
}