curl --request POST \
  --url https://api.example.com/api/v2/clients \
  --header 'Content-Type: application/json' \
  --data '
{
  "firstName": "<string>",
  "lastName": "<string>",
  "emailAddress": "jsmith@example.com",
  "title": "<string>",
  "companyName": "<string>",
  "telephoneNumber": "<string>",
  "address": {
    "line_1": "<string>",
    "postcode": "<string>",
    "line_2": "<string>",
    "line_3": "<string>",
    "post_town": "<string>",
    "county": "<string>",
    "uprn": "<string>"
  }
}
'

import requests

url = "https://api.example.com/api/v2/clients"

payload = {
    "firstName": "<string>",
    "lastName": "<string>",
    "emailAddress": "jsmith@example.com",
    "title": "<string>",
    "companyName": "<string>",
    "telephoneNumber": "<string>",
    "address": {
        "line_1": "<string>",
        "postcode": "<string>",
        "line_2": "<string>",
        "line_3": "<string>",
        "post_town": "<string>",
        "county": "<string>",
        "uprn": "<string>"
    }
}
headers = {"Content-Type": "application/json"}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    firstName: '<string>',
    lastName: '<string>',
    emailAddress: 'jsmith@example.com',
    title: '<string>',
    companyName: '<string>',
    telephoneNumber: '<string>',
    address: {
      line_1: '<string>',
      postcode: '<string>',
      line_2: '<string>',
      line_3: '<string>',
      post_town: '<string>',
      county: '<string>',
      uprn: '<string>'
    }
  })
};

fetch('https://api.example.com/api/v2/clients', 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://api.example.com/api/v2/clients",
  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([
    'firstName' => '<string>',
    'lastName' => '<string>',
    'emailAddress' => 'jsmith@example.com',
    'title' => '<string>',
    'companyName' => '<string>',
    'telephoneNumber' => '<string>',
    'address' => [
        'line_1' => '<string>',
        'postcode' => '<string>',
        'line_2' => '<string>',
        'line_3' => '<string>',
        'post_town' => '<string>',
        'county' => '<string>',
        'uprn' => '<string>'
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($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://api.example.com/api/v2/clients"

	payload := strings.NewReader("{\n  \"firstName\": \"<string>\",\n  \"lastName\": \"<string>\",\n  \"emailAddress\": \"jsmith@example.com\",\n  \"title\": \"<string>\",\n  \"companyName\": \"<string>\",\n  \"telephoneNumber\": \"<string>\",\n  \"address\": {\n    \"line_1\": \"<string>\",\n    \"postcode\": \"<string>\",\n    \"line_2\": \"<string>\",\n    \"line_3\": \"<string>\",\n    \"post_town\": \"<string>\",\n    \"county\": \"<string>\",\n    \"uprn\": \"<string>\"\n  }\n}")

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

	req.Header.Add("Content-Type", "application/json")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.example.com/api/v2/clients")
  .header("Content-Type", "application/json")
  .body("{\n  \"firstName\": \"<string>\",\n  \"lastName\": \"<string>\",\n  \"emailAddress\": \"jsmith@example.com\",\n  \"title\": \"<string>\",\n  \"companyName\": \"<string>\",\n  \"telephoneNumber\": \"<string>\",\n  \"address\": {\n    \"line_1\": \"<string>\",\n    \"postcode\": \"<string>\",\n    \"line_2\": \"<string>\",\n    \"line_3\": \"<string>\",\n    \"post_town\": \"<string>\",\n    \"county\": \"<string>\",\n    \"uprn\": \"<string>\"\n  }\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.example.com/api/v2/clients")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"firstName\": \"<string>\",\n  \"lastName\": \"<string>\",\n  \"emailAddress\": \"jsmith@example.com\",\n  \"title\": \"<string>\",\n  \"companyName\": \"<string>\",\n  \"telephoneNumber\": \"<string>\",\n  \"address\": {\n    \"line_1\": \"<string>\",\n    \"postcode\": \"<string>\",\n    \"line_2\": \"<string>\",\n    \"line_3\": \"<string>\",\n    \"post_town\": \"<string>\",\n    \"county\": \"<string>\",\n    \"uprn\": \"<string>\"\n  }\n}"

response = http.request(request)
puts response.read_body

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "firstName": "<string>",
  "lastName": "<string>",
  "emailAddress": "jsmith@example.com",
  "title": "<string>",
  "middleName": "<string>",
  "companyName": "<string>",
  "telephoneNumber": "<string>",
  "altTelephoneNumber": "<string>",
  "pronouns": "<string>",
  "communicationPreferences": {
    "email": true,
    "phone": true,
    "sms": true,
    "post": true
  },
  "avatarUrl": "<string>",
  "dob": "<string>",
  "nationality": "<string>",
  "niNumber": "<string>",
  "occupation": "<string>",
  "address": {
    "line_1": "<string>",
    "line_2": "<string>",
    "line_3": "<string>",
    "post_town": "<string>",
    "county": "<string>",
    "postcode": "<string>",
    "uprn": "<string>"
  }
}

{
  "message": "<string>",
  "errors": {}
}