curl --request GET \
  --url https://alphainsider.com/api/getInvoicePdf \
  --header 'Authorization: <authorization>'

const options = {method: 'GET', headers: {Authorization: '<authorization>'}};

fetch('https://alphainsider.com/api/getInvoicePdf', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://alphainsider.com/api/getInvoicePdf"

headers = {"Authorization": "<authorization>"}

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

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://alphainsider.com/api/getInvoicePdf",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "Authorization: <authorization>"
  ],
]);

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

curl_close($curl);

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

package main

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

func main() {

	url := "https://alphainsider.com/api/getInvoicePdf"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "<authorization>")

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

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

	fmt.Println(string(body))

}

"<< PDF FILE >>"

{
  "success": false,
  "response": "Request failed."
}

{
  "success": false,
  "response": "Authentication failed."
}