curl --request POST \
  --url https://your-instance.example.com/api/messages/upload-attachment \
  --header 'Content-Type: multipart/form-data' \
  --form file='@example-file' \
  --form webchatConfigId=64a1b2c3d4e5f60012345678

import requests

url = "https://your-instance.example.com/api/messages/upload-attachment"

files = { "file": ("example-file", open("example-file", "rb")) }
payload = { "webchatConfigId": "64a1b2c3d4e5f60012345678" }

response = requests.post(url, data=payload, files=files)

print(response.text)

const form = new FormData();
form.append('file', '<binary: receipt.png>');
form.append('webchatConfigId', '64a1b2c3d4e5f60012345678');

const options = {method: 'POST'};

options.body = form;

fetch('https://your-instance.example.com/api/messages/upload-attachment', 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://your-instance.example.com/api/messages/upload-attachment",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<binary: receipt.png>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webchatConfigId\"\r\n\r\n64a1b2c3d4e5f60012345678\r\n-----011000010111000001101001--",
  CURLOPT_HTTPHEADER => [
    "Content-Type: multipart/form-data"
  ],
]);

$response = curl_exec($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://your-instance.example.com/api/messages/upload-attachment"

	payload := strings.NewReader("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<binary: receipt.png>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webchatConfigId\"\r\n\r\n64a1b2c3d4e5f60012345678\r\n-----011000010111000001101001--")

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

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://your-instance.example.com/api/messages/upload-attachment")
  .body("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<binary: receipt.png>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webchatConfigId\"\r\n\r\n64a1b2c3d4e5f60012345678\r\n-----011000010111000001101001--")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://your-instance.example.com/api/messages/upload-attachment")

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

request = Net::HTTP::Post.new(url)
request.body = "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<binary: receipt.png>\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"webchatConfigId\"\r\n\r\n64a1b2c3d4e5f60012345678\r\n-----011000010111000001101001--"

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

{
  "success": true,
  "attachment": {
    "storageKey": "messages/65a0e0e0e0e0e0e0e0e0e0e0/msg_67b0/photo.jpg",
    "filename": "photo.jpg",
    "contentType": "image/jpeg",
    "size": 184221
  }
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}

{
  "error": "Too many requests",
  "limit": 20,
  "currentCount": 21,
  "resetIn": 42,
  "message": "Please wait before uploading more attachments"
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}