curl --request POST \
  --url https://demo.onlinebillingform.com/api/v2/setting/invoice \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "prefix": "<string>",
  "orderReturnURL": "<string>",
  "startNumber": 123,
  "paymentsDue": 123,
  "lateFees": 123,
  "lateFeesTax": 123,
  "reminders": 123,
  "reminders4suspend": 123,
  "days2send": 123,
  "total-order": [
    "<string>"
  ],
  "defaultCurrency": 123,
  "currency": [
    "<string>"
  ],
  "exchangerate": 123,
  "vat": 123,
  "vat.name": [
    "<string>"
  ],
  "vat.number": [
    "<string>"
  ],
  "companyRegistration": "<string>",
  "fixedDiscount": true,
  "discountCode": true
}
'

import requests

url = "https://demo.onlinebillingform.com/api/v2/setting/invoice"

payload = {
    "prefix": "<string>",
    "orderReturnURL": "<string>",
    "startNumber": 123,
    "paymentsDue": 123,
    "lateFees": 123,
    "lateFeesTax": 123,
    "reminders": 123,
    "reminders4suspend": 123,
    "days2send": 123,
    "total-order": ["<string>"],
    "defaultCurrency": 123,
    "currency": ["<string>"],
    "exchangerate": 123,
    "vat": 123,
    "vat.name": ["<string>"],
    "vat.number": ["<string>"],
    "companyRegistration": "<string>",
    "fixedDiscount": True,
    "discountCode": True
}
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({
    prefix: '<string>',
    orderReturnURL: '<string>',
    startNumber: 123,
    paymentsDue: 123,
    lateFees: 123,
    lateFeesTax: 123,
    reminders: 123,
    reminders4suspend: 123,
    days2send: 123,
    'total-order': ['<string>'],
    defaultCurrency: 123,
    currency: ['<string>'],
    exchangerate: 123,
    vat: 123,
    'vat.name': ['<string>'],
    'vat.number': ['<string>'],
    companyRegistration: '<string>',
    fixedDiscount: true,
    discountCode: true
  })
};

fetch('https://demo.onlinebillingform.com/api/v2/setting/invoice', 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/setting/invoice",
  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([
    'prefix' => '<string>',
    'orderReturnURL' => '<string>',
    'startNumber' => 123,
    'paymentsDue' => 123,
    'lateFees' => 123,
    'lateFeesTax' => 123,
    'reminders' => 123,
    'reminders4suspend' => 123,
    'days2send' => 123,
    'total-order' => [
        '<string>'
    ],
    'defaultCurrency' => 123,
    'currency' => [
        '<string>'
    ],
    'exchangerate' => 123,
    'vat' => 123,
    'vat.name' => [
        '<string>'
    ],
    'vat.number' => [
        '<string>'
    ],
    'companyRegistration' => '<string>',
    'fixedDiscount' => true,
    'discountCode' => true
  ]),
  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/setting/invoice"

	payload := strings.NewReader("{\n  \"prefix\": \"<string>\",\n  \"orderReturnURL\": \"<string>\",\n  \"startNumber\": 123,\n  \"paymentsDue\": 123,\n  \"lateFees\": 123,\n  \"lateFeesTax\": 123,\n  \"reminders\": 123,\n  \"reminders4suspend\": 123,\n  \"days2send\": 123,\n  \"total-order\": [\n    \"<string>\"\n  ],\n  \"defaultCurrency\": 123,\n  \"currency\": [\n    \"<string>\"\n  ],\n  \"exchangerate\": 123,\n  \"vat\": 123,\n  \"vat.name\": [\n    \"<string>\"\n  ],\n  \"vat.number\": [\n    \"<string>\"\n  ],\n  \"companyRegistration\": \"<string>\",\n  \"fixedDiscount\": true,\n  \"discountCode\": true\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/setting/invoice")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"prefix\": \"<string>\",\n  \"orderReturnURL\": \"<string>\",\n  \"startNumber\": 123,\n  \"paymentsDue\": 123,\n  \"lateFees\": 123,\n  \"lateFeesTax\": 123,\n  \"reminders\": 123,\n  \"reminders4suspend\": 123,\n  \"days2send\": 123,\n  \"total-order\": [\n    \"<string>\"\n  ],\n  \"defaultCurrency\": 123,\n  \"currency\": [\n    \"<string>\"\n  ],\n  \"exchangerate\": 123,\n  \"vat\": 123,\n  \"vat.name\": [\n    \"<string>\"\n  ],\n  \"vat.number\": [\n    \"<string>\"\n  ],\n  \"companyRegistration\": \"<string>\",\n  \"fixedDiscount\": true,\n  \"discountCode\": true\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://demo.onlinebillingform.com/api/v2/setting/invoice")

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  \"prefix\": \"<string>\",\n  \"orderReturnURL\": \"<string>\",\n  \"startNumber\": 123,\n  \"paymentsDue\": 123,\n  \"lateFees\": 123,\n  \"lateFeesTax\": 123,\n  \"reminders\": 123,\n  \"reminders4suspend\": 123,\n  \"days2send\": 123,\n  \"total-order\": [\n    \"<string>\"\n  ],\n  \"defaultCurrency\": 123,\n  \"currency\": [\n    \"<string>\"\n  ],\n  \"exchangerate\": 123,\n  \"vat\": 123,\n  \"vat.name\": [\n    \"<string>\"\n  ],\n  \"vat.number\": [\n    \"<string>\"\n  ],\n  \"companyRegistration\": \"<string>\",\n  \"fixedDiscount\": true,\n  \"discountCode\": true\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."
    ]
  }
}