curl --request GET \
  --url https://apidjonanko.tech/web-merchant/get-balance \
  --header 'authenticationtoken: <api-key>'

const options = {method: 'GET', headers: {authenticationtoken: '<api-key>'}};

fetch('https://apidjonanko.tech/web-merchant/get-balance', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://apidjonanko.tech/web-merchant/get-balance"

headers = {"authenticationtoken": "<api-key>"}

response = requests.get(url, headers=headers)

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://apidjonanko.tech/web-merchant/get-balance",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "authenticationtoken: <api-key>"
  ],
]);

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

curl_close($curl);

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

"125000.00"

{
  "statusCode": 401,
  "message": "Invalid API credentials",
  "error": "Unauthorized"
}