curl --request POST \
  --url https://api.natural.com/chargebacks/{chargebackId}/files \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: multipart/form-data' \
  --header 'Idempotency-Key: <idempotency-key>' \
  --form file='@example-file'

import requests

url = "https://api.natural.com/chargebacks/{chargebackId}/files"

files = { "file": ("example-file", open("example-file", "rb")) }
headers = {
    "Idempotency-Key": "<idempotency-key>",
    "Authorization": "Bearer <token>"
}

response = requests.post(url, files=files, headers=headers)

print(response.text)

const form = new FormData();
form.append('file', '<string>');

const options = {
  method: 'POST',
  headers: {'Idempotency-Key': '<idempotency-key>', Authorization: 'Bearer <token>'}
};

options.body = form;

fetch('https://api.natural.com/chargebacks/{chargebackId}/files', 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://api.natural.com/chargebacks/{chargebackId}/files",
  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<string>\r\n-----011000010111000001101001--",
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: multipart/form-data",
    "Idempotency-Key: <idempotency-key>"
  ],
]);

$response = curl_exec($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://api.natural.com/chargebacks/{chargebackId}/files"

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

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

	req.Header.Add("Idempotency-Key", "<idempotency-key>")
	req.Header.Add("Authorization", "Bearer <token>")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.natural.com/chargebacks/{chargebackId}/files")
  .header("Idempotency-Key", "<idempotency-key>")
  .header("Authorization", "Bearer <token>")
  .body("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<string>\r\n-----011000010111000001101001--")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.natural.com/chargebacks/{chargebackId}/files")

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

request = Net::HTTP::Post.new(url)
request["Idempotency-Key"] = '<idempotency-key>'
request["Authorization"] = 'Bearer <token>'
request.body = "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"example-file\"\r\nContent-Type: application/octet-stream\r\n\r\n<string>\r\n-----011000010111000001101001--"

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

{
  "data": {
    "id": "evf_019d0a1b2c3d4e5f60718293a4b5c701",
    "type": "chargebackEvidenceFile",
    "attributes": {
      "filename": "delivery-confirmation.pdf",
      "contentType": "application/pdf",
      "sizeBytes": 2048,
      "pageCount": 1,
      "createdAt": "2026-09-17T12:01:00.000Z"
    },
    "relationships": {
      "chargeback": {
        "data": {
          "type": "chargeback",
          "id": "cbk_019d0a1b2c3d4e5f60718293a4b5c700"
        }
      }
    }
  }
}

{
  "errors": [
    {
      "code": "invalid_value",
      "detail": "The information you entered isn't valid. Please check it and try again.",
      "status": "400",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "unauthenticated",
      "detail": "Authentication is required.",
      "status": "401",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "forbidden",
      "detail": "You do not have permission to perform this action.",
      "status": "403",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "not_found",
      "detail": "The requested resource was not found.",
      "status": "404",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "conflict",
      "detail": "The request conflicts with the current resource state.",
      "status": "409",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "invalid_value",
      "detail": "Too big: expected string to have <=80 characters",
      "status": "422",
      "source": {
        "pointer": "/data/attributes/description"
      },
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "mfa_required",
      "detail": "MFA verification required",
      "status": "428",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "rate_limited",
      "detail": "Too many requests. Please try again later.",
      "status": "429",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "server_error",
      "detail": "Something went wrong.",
      "status": "500",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "not_implemented",
      "detail": "This operation is not available.",
      "status": "501",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "bad_gateway",
      "detail": "We couldn't complete that request because one of Natural's services returned an unexpected response. Please try again.",
      "status": "502",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}

{
  "errors": [
    {
      "code": "service_unavailable",
      "detail": "The service is temporarily unavailable.",
      "status": "503",
      "meta": {
        "supportId": "req_a1b2c3d4e5f6"
      }
    }
  ]
}