const res = await fetch('https://app.trdrs.co/api/trading/order-size', {
  method: 'POST',
  headers: {
    'content-type': 'application/json',
    Authorization: `Bearer ${process.env.TRDRS_API_KEY}`,
  },
  body: JSON.stringify({
    "instrument": "ESU6",
    "side": "buy",
    "size": {
      "kind": "margin",
      "amount": "5000"
    },
    "orderType": "market"
  }),
})
const data = await res.json()

curl -X POST 'https://app.trdrs.co/api/trading/order-size' \
  -H "Authorization: Bearer $TRDRS_API_KEY" \
  -H 'content-type: application/json' \
  -d '{"instrument":"ESU6","side":"buy","size":{"kind":"margin","amount":"5000"},"orderType":"market"}'

import requests

url = "https://app.trdrs.co/api/trading/order-size"

payload = {
    "instrument": "ESU6",
    "side": "buy",
    "size": {
        "kind": "margin",
        "amount": "5000"
    },
    "orderType": "market"
}
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://app.trdrs.co/api/trading/order-size",
  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([
    'instrument' => 'ESU6',
    'side' => 'buy',
    'size' => [
        'kind' => 'margin',
        'amount' => '5000'
    ],
    'orderType' => 'market'
  ]),
  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://app.trdrs.co/api/trading/order-size"

	payload := strings.NewReader("{\n  \"instrument\": \"ESU6\",\n  \"side\": \"buy\",\n  \"size\": {\n    \"kind\": \"margin\",\n    \"amount\": \"5000\"\n  },\n  \"orderType\": \"market\"\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://app.trdrs.co/api/trading/order-size")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"instrument\": \"ESU6\",\n  \"side\": \"buy\",\n  \"size\": {\n    \"kind\": \"margin\",\n    \"amount\": \"5000\"\n  },\n  \"orderType\": \"market\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.trdrs.co/api/trading/order-size")

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  \"instrument\": \"ESU6\",\n  \"side\": \"buy\",\n  \"size\": {\n    \"kind\": \"margin\",\n    \"amount\": \"5000\"\n  },\n  \"orderType\": \"market\"\n}"

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

{
  "instrument": "MESU6",
  "qty": 3,
  "cost": "4626.30",
  "smallest": "1542.10",
  "available": "10000.00",
  "currency": "USD"
}

{
  "error": "invalid_instrument"
}

{
  "error": "invalid_instrument"
}

{
  "error": "invalid_instrument"
}