curl --request POST \
  --url https://demo.onlinebillingform.com/api/v2/customer/update \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": 123,
  "name": "<string>",
  "address_1": "<string>",
  "city": "<string>",
  "county_id": 123,
  "country_id": 123,
  "postal_code": "<string>",
  "phone": "<string>",
  "username": "jsmith@example.com",
  "address_2": "<string>",
  "fax": "<string>",
  "password": "<string>",
  "website": "<string>",
  "credit": 123,
  "business_name": "<string>",
  "comment": "<string>",
  "vat": 123
}
'

import requests

url = "https://demo.onlinebillingform.com/api/v2/customer/update"

payload = {
    "id": 123,
    "name": "<string>",
    "address_1": "<string>",
    "city": "<string>",
    "county_id": 123,
    "country_id": 123,
    "postal_code": "<string>",
    "phone": "<string>",
    "username": "jsmith@example.com",
    "address_2": "<string>",
    "fax": "<string>",
    "password": "<string>",
    "website": "<string>",
    "credit": 123,
    "business_name": "<string>",
    "comment": "<string>",
    "vat": 123
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    id: 123,
    name: '<string>',
    address_1: '<string>',
    city: '<string>',
    county_id: 123,
    country_id: 123,
    postal_code: '<string>',
    phone: '<string>',
    username: 'jsmith@example.com',
    address_2: '<string>',
    fax: '<string>',
    password: '<string>',
    website: '<string>',
    credit: 123,
    business_name: '<string>',
    comment: '<string>',
    vat: 123
  })
};

fetch('https://demo.onlinebillingform.com/api/v2/customer/update', 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://demo.onlinebillingform.com/api/v2/customer/update",
  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([
    'id' => 123,
    'name' => '<string>',
    'address_1' => '<string>',
    'city' => '<string>',
    'county_id' => 123,
    'country_id' => 123,
    'postal_code' => '<string>',
    'phone' => '<string>',
    'username' => 'jsmith@example.com',
    'address_2' => '<string>',
    'fax' => '<string>',
    'password' => '<string>',
    'website' => '<string>',
    'credit' => 123,
    'business_name' => '<string>',
    'comment' => '<string>',
    'vat' => 123
  ]),
  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;
}

package main

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

func main() {

	url := "https://demo.onlinebillingform.com/api/v2/customer/update"

	payload := strings.NewReader("{\n  \"id\": 123,\n  \"name\": \"<string>\",\n  \"address_1\": \"<string>\",\n  \"city\": \"<string>\",\n  \"county_id\": 123,\n  \"country_id\": 123,\n  \"postal_code\": \"<string>\",\n  \"phone\": \"<string>\",\n  \"username\": \"jsmith@example.com\",\n  \"address_2\": \"<string>\",\n  \"fax\": \"<string>\",\n  \"password\": \"<string>\",\n  \"website\": \"<string>\",\n  \"credit\": 123,\n  \"business_name\": \"<string>\",\n  \"comment\": \"<string>\",\n  \"vat\": 123\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	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://demo.onlinebillingform.com/api/v2/customer/update")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"id\": 123,\n  \"name\": \"<string>\",\n  \"address_1\": \"<string>\",\n  \"city\": \"<string>\",\n  \"county_id\": 123,\n  \"country_id\": 123,\n  \"postal_code\": \"<string>\",\n  \"phone\": \"<string>\",\n  \"username\": \"jsmith@example.com\",\n  \"address_2\": \"<string>\",\n  \"fax\": \"<string>\",\n  \"password\": \"<string>\",\n  \"website\": \"<string>\",\n  \"credit\": 123,\n  \"business_name\": \"<string>\",\n  \"comment\": \"<string>\",\n  \"vat\": 123\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://demo.onlinebillingform.com/api/v2/customer/update")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"id\": 123,\n  \"name\": \"<string>\",\n  \"address_1\": \"<string>\",\n  \"city\": \"<string>\",\n  \"county_id\": 123,\n  \"country_id\": 123,\n  \"postal_code\": \"<string>\",\n  \"phone\": \"<string>\",\n  \"username\": \"jsmith@example.com\",\n  \"address_2\": \"<string>\",\n  \"fax\": \"<string>\",\n  \"password\": \"<string>\",\n  \"website\": \"<string>\",\n  \"credit\": 123,\n  \"business_name\": \"<string>\",\n  \"comment\": \"<string>\",\n  \"vat\": 123\n}"

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

{
  "success": true
}

{
  "success": false,
  "errors": "Invalid API Key"
}

{
  "success": false,
  "errors": "Insufficient permissions for this endpoint."
}

{
  "success": false,
  "errors": {
    "id": [
      "The id field is required."
    ]
  }
}