curl --request POST \
  --url https://{host}/v1/users \
  --header 'Content-Type: application/vnd.api+json' \
  --data '
{
  "data": {
    "type": "users",
    "attributes": {
      "clientId": "9f2c1b7e-4d3a-4f61-9c8b-2e5a7d0f1b34",
      "email": "jeffrey@example.test",
      "password": "the-one-they-chose",
      "name": "Jeffrey",
      "lastName": "Ponsen",
      "locale": "nl",
      "scope": "internal messages:read messages:write"
    }
  }
}
'

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/vnd.api+json'},
  body: JSON.stringify({
    data: {
      type: 'users',
      attributes: {
        clientId: '9f2c1b7e-4d3a-4f61-9c8b-2e5a7d0f1b34',
        email: 'jeffrey@example.test',
        password: 'the-one-they-chose',
        name: 'Jeffrey',
        lastName: 'Ponsen',
        locale: 'nl',
        scope: 'internal messages:read messages:write'
      }
    }
  })
};

fetch('https://{host}/v1/users', 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://{host}/v1/users",
  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([
    'data' => [
        'type' => 'users',
        'attributes' => [
                'clientId' => '9f2c1b7e-4d3a-4f61-9c8b-2e5a7d0f1b34',
                'email' => 'jeffrey@example.test',
                'password' => 'the-one-they-chose',
                'name' => 'Jeffrey',
                'lastName' => 'Ponsen',
                'locale' => 'nl',
                'scope' => 'internal messages:read messages:write'
        ]
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/vnd.api+json"
  ],
]);

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

curl_close($curl);

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

import requests

url = "https://{host}/v1/users"

payload = { "data": {
        "type": "users",
        "attributes": {
            "clientId": "9f2c1b7e-4d3a-4f61-9c8b-2e5a7d0f1b34",
            "email": "jeffrey@example.test",
            "password": "the-one-they-chose",
            "name": "Jeffrey",
            "lastName": "Ponsen",
            "locale": "nl",
            "scope": "internal messages:read messages:write"
        }
    } }
headers = {"Content-Type": "application/vnd.api+json"}

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

print(response.text)

{
  "data": {
    "type": "users",
    "id": "15",
    "attributes": {
      "email": "jeffrey@example.test",
      "name": "Jeffrey",
      "lastName": "Ponsen",
      "locale": "nl",
      "emailVerified": false
    }
  },
  "meta": {
    "session": {
      "accessToken": "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9…",
      "refreshToken": "def50200f1e3…",
      "tokenType": "Bearer",
      "expiresIn": 3600
    }
  }
}

{
  "errors": [
    {
      "status": "404",
      "code": "watch_reserved",
      "title": "Not Found",
      "detail": "<string>",
      "meta": {},
      "source": {
        "pointer": "/data/attributes/reference",
        "parameter": "<string>"
      }
    }
  ],
  "jsonapi": {
    "version": "1.0"
  }
}

{
  "errors": [
    {
      "status": "422",
      "code": "implausible_email",
      "title": "Unprocessable Entity",
      "detail": "Did you mean jan@gmail.com?",
      "source": {
        "pointer": "/data/attributes/email"
      },
      "meta": {
        "suggestion": "jan@gmail.com",
        "domain": "gnail.com"
      }
    }
  ]
}