curl --request POST \
  --url https://api.tilta.io/v1/contacts \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "buyer_external_id": "<string>",
  "first_name": "<string>",
  "last_name": "<string>",
  "email": "jsmith@example.com",
  "phone": "+491711010101",
  "assign_to_all_invoices": true,
  "address": {
    "postcode": "12345",
    "city": "Berlin",
    "street": "Example Street",
    "house": "42b",
    "additional": "c/o Testimonial"
  },
  "external_id": "<string>"
}
'

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    buyer_external_id: '<string>',
    first_name: '<string>',
    last_name: '<string>',
    email: 'jsmith@example.com',
    phone: '+491711010101',
    assign_to_all_invoices: true,
    address: {
      postcode: '12345',
      city: 'Berlin',
      street: 'Example Street',
      house: '42b',
      additional: 'c/o Testimonial'
    },
    external_id: '<string>'
  })
};

fetch('https://api.tilta.io/v1/contacts', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.tilta.io/v1/contacts"

payload = {
    "buyer_external_id": "<string>",
    "first_name": "<string>",
    "last_name": "<string>",
    "email": "jsmith@example.com",
    "phone": "+491711010101",
    "assign_to_all_invoices": True,
    "address": {
        "postcode": "12345",
        "city": "Berlin",
        "street": "Example Street",
        "house": "42b",
        "additional": "c/o Testimonial"
    },
    "external_id": "<string>"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.tilta.io/v1/contacts",
  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([
    'buyer_external_id' => '<string>',
    'first_name' => '<string>',
    'last_name' => '<string>',
    'email' => 'jsmith@example.com',
    'phone' => '+491711010101',
    'assign_to_all_invoices' => true,
    'address' => [
        'postcode' => '12345',
        'city' => 'Berlin',
        'street' => 'Example Street',
        'house' => '42b',
        'additional' => 'c/o Testimonial'
    ],
    'external_id' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

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

curl_close($curl);

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

{
  "external_id": "<string>",
  "buyer_external_id": "<string>",
  "assign_to_all_invoices": true,
  "created_at": 1582896122,
  "updated_at": 1582896122,
  "salutation": "MR",
  "first_name": "<string>",
  "last_name": "<string>",
  "email": "jsmith@example.com",
  "phone": "+491711010101",
  "address": {
    "postcode": "12345",
    "city": "Berlin",
    "country": "AF",
    "street": "Example Street",
    "house": "42b",
    "additional": "c/o Testimonial"
  }
}

{
  "code": "BAD_REQUEST",
  "error": "Request validation failed. 1 issue found.",
  "issues": [
    {
      "code": "INVALID_TYPE",
      "path": "body.registered_at",
      "message": "Invalid type"
    }
  ]
}

{
  "error": "Unauthorized",
  "code": "UNAUTHORIZED"
}