curl --request POST \
  --url https://cloudapi.mailercloud.com/v1/contacts/batch \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: <content-type>' \
  --data '
{
  "contacts": [
    {
      "city": "string",
      "country": "string",
      "custom_fields": {
        "enc_id1": "string",
        "enc_id2": 0
      },
      "department": "string",
      "email": "string",
      "industry": "string",
      "job_title": "string",
      "last_name": "string",
      "lead_source": "string",
      "middle_name": "string",
      "name": "string",
      "company_name": "string",
      "phone": "string",
      "salary": 0,
      "state": "string",
      "postal_code": "string",
      "tags": [
        "string"
      ]
    }
  ],
  "list_id": "string"
}
'

import requests

url = "https://cloudapi.mailercloud.com/v1/contacts/batch"

payload = {
    "contacts": [
        {
            "city": "string",
            "country": "string",
            "custom_fields": {
                "enc_id1": "string",
                "enc_id2": 0
            },
            "department": "string",
            "email": "string",
            "industry": "string",
            "job_title": "string",
            "last_name": "string",
            "lead_source": "string",
            "middle_name": "string",
            "name": "string",
            "company_name": "string",
            "phone": "string",
            "salary": 0,
            "state": "string",
            "postal_code": "string",
            "tags": ["string"]
        }
    ],
    "list_id": "string"
}
headers = {
    "Content-Type": "<content-type>",
    "Authorization": "<api-key>"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'Content-Type': '<content-type>', Authorization: '<api-key>'},
  body: JSON.stringify({
    contacts: [
      {
        city: 'string',
        country: 'string',
        custom_fields: {enc_id1: 'string', enc_id2: 0},
        department: 'string',
        email: 'string',
        industry: 'string',
        job_title: 'string',
        last_name: 'string',
        lead_source: 'string',
        middle_name: 'string',
        name: 'string',
        company_name: 'string',
        phone: 'string',
        salary: 0,
        state: 'string',
        postal_code: 'string',
        tags: ['string']
      }
    ],
    list_id: 'string'
  })
};

fetch('https://cloudapi.mailercloud.com/v1/contacts/batch', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://cloudapi.mailercloud.com/v1/contacts/batch",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'contacts' => [
        [
                'city' => 'string',
                'country' => 'string',
                'custom_fields' => [
                                'enc_id1' => 'string',
                                'enc_id2' => 0
                ],
                'department' => 'string',
                'email' => 'string',
                'industry' => 'string',
                'job_title' => 'string',
                'last_name' => 'string',
                'lead_source' => 'string',
                'middle_name' => 'string',
                'name' => 'string',
                'company_name' => 'string',
                'phone' => 'string',
                'salary' => 0,
                'state' => 'string',
                'postal_code' => 'string',
                'tags' => [
                                'string'
                ]
        ]
    ],
    'list_id' => 'string'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: <api-key>",
    "Content-Type: <content-type>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://cloudapi.mailercloud.com/v1/contacts/batch"

	payload := strings.NewReader("{\n  \"contacts\": [\n    {\n      \"city\": \"string\",\n      \"country\": \"string\",\n      \"custom_fields\": {\n        \"enc_id1\": \"string\",\n        \"enc_id2\": 0\n      },\n      \"department\": \"string\",\n      \"email\": \"string\",\n      \"industry\": \"string\",\n      \"job_title\": \"string\",\n      \"last_name\": \"string\",\n      \"lead_source\": \"string\",\n      \"middle_name\": \"string\",\n      \"name\": \"string\",\n      \"company_name\": \"string\",\n      \"phone\": \"string\",\n      \"salary\": 0,\n      \"state\": \"string\",\n      \"postal_code\": \"string\",\n      \"tags\": [\n        \"string\"\n      ]\n    }\n  ],\n  \"list_id\": \"string\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Content-Type", "<content-type>")
	req.Header.Add("Authorization", "<api-key>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

{
  "data": {
    "inserted": 2,
    "skipped": 1,
    "submitted": 3,
    "updated": 0
  },
  "message": "Batch contacts processed"
}

{
  "error": {
    "field": "email",
    "message": "Invalid email"
  }
}

{
  "errors": [
    {
      "field": "",
      "message": "Authorization failed"
    }
  ]
}