Request
curl -X POST -H "Content-Type: application/json" -d \
'{
   "key": "Loremipsumdolorsitametconsecteturadipiscingelitlaoreet",
   "owner_code": "netstorming",
   "dry_run": true,
   "customers": [
     {
       "code": "test01",
       "name": "Test customer from API 1",
       "address": "test1",
       "zip": "test1",
       "mailstaff": "test1@netstorming.net",
       "notify_lang": "it",
       "booking_online": true,
       "blocked_in_deadline": false,
       "credit_card": true,
       "telephone": "0418877780",
       "fax": "0418877781",
       "currency": "EUR",
       "admin_user_name": "test1 usr",
       "admin_user_email": "test1@netstorming.net",
       "admin_user_login": "test1",
       "admin_user_psw": "test1",
       "country": "IT",
       "city": "VCEI"
     },
     {
       "code": "INVALID01",
       "name": "Test with invalid data",
       "zip": "test1",
       "mailstaff": "test1@netstorming.net",
       "notify_lang": "bu",
       "booking_online": 42,
       "blocked_in_deadline": false,
       "credit_card": true,
       "telephone": "0418877780",
       "fax": "0418877781",
       "currency": "BGK",
       "admin_user_name": "test1 usr",
       "admin_user_email": "test1@netstorming.net",
       "admin_user_login": "test1",
       "admin_user_psw": "test1",
       "country": "IT",
       "city": "VCEI"
     }
   ]
 }' https://test.netstorming.net/api/customers/insert
Response
{
  "dry_run": true,
  "results": [
    {
      "code": "test01",
      "customer": false,
      "user": false
    }
  ],
  "errors": [
    {
      "line\/index": 1,
      "errors": [
        "missing address",
        "invalid notify_lang",
        "invalid booking_online (valid values: yes, no, y, n, true, false, 1, 0)"
      ]
    }
  ]
}

NOTE: The results are FALSE due to dry run