How to sync supplier invoices and attachments

Automatically pulling supplier invoices into your system removes the need for manual data entry and gives your finance team real-time visibility into what is owed and when. In this guide, we will fetch all supplier invoices updated since the last sync, paginate through results, and download their attachments; using the same polling pattern as client invoices, with different endpoints and filters.

Example: A spend management tool syncs supplier invoices from Qonto nightly to match them against purchase orders and flag any discrepancies before payment.

Prerequisites:

At least one supplier invoice exists in Qonto.
Scopes: supplier_invoice.read, attachment.read

Initialize the sync timestamp

Same approach as client invoices: load the last successful sync timestamp from your database and capture the current time.

Python
Node.js

from datetime import datetime, timezone

BASE_URL = "https://thirdparty.qonto.com/v2"
headers = {"Authorization": "Bearer {your_access_token}"}

last_sync_at = "2026-01-01T00:00:00Z"  # Load from your database
current_sync_at = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")

const BASE_URL = "https://thirdparty.qonto.com/v2";
const headers = { Authorization: "Bearer {your_access_token}" };

const lastSyncAt = "2026-01-01T00:00:00Z"; // Load from your database
const currentSyncAt = new Date().toISOString();

Fetch all supplier invoices updated in the time window

List supplier invoices updated between your last sync and now, sorted chronologically and paginated.Endpoint: List supplier invoices

OAuth scope required: supplier_invoice.read.

Additional filters are available: filter[status] (e.g., to_review, to_pay, paid), filter[due_date], and filter[created_at_from] / filter[created_at_to].

Python
Node.js

def fetch_all_supplier_invoices(last_sync_at, current_sync_at):
    invoices = []
    page = 1

    while True:
        response = requests.get(
            f"{BASE_URL}/supplier_invoices",
            headers=headers,
            params={
                "filter[updated_at_from]": last_sync_at,
                "filter[updated_at_to]": current_sync_at,
                "sort_by": "updated_at:asc",  # Process chronologically
                "per_page": 100,
                "page": page,
            },
        )
        response.raise_for_status()
        data = response.json()

        invoices.extend(data["supplier_invoices"])

        if data["meta"]["next_page"] is None:
            break
        page = data["meta"]["next_page"]

    return invoices

invoices = fetch_all_supplier_invoices(last_sync_at, current_sync_at)
print(f"Fetched {len(invoices)} supplier invoices")

async function fetchAllSupplierInvoices(lastSyncAt, currentSyncAt) {
  const invoices = [];
  let page = 1;

  while (true) {
    const params = new URLSearchParams({
      "filter[updated_at_from]": lastSyncAt,
      "filter[updated_at_to]": currentSyncAt,
      sort_by: "updated_at:asc", // Process chronologically
      per_page: 100,
      page,
    });
    const response = await fetch(`${BASE_URL}/supplier_invoices?${params}`, { headers });
    if (!response.ok) throw new Error(`HTTP ${response.status}`);

    const data = await response.json();
    invoices.push(...data.supplier_invoices);

    if (data.meta.next_page === null) break;
    page = data.meta.next_page;
  }

  return invoices;
}

const invoices = await fetchAllSupplierInvoices(lastSyncAt, currentSyncAt);
console.log(`Fetched ${invoices.length} supplier invoices`);

Retrieve and download attachments

For each invoice with an attachment_id, fetch the attachment and download the file. The attachment URL expires in 30 minutes — download immediately.Endpoint: Retrieve an attachment

OAuth scope required: attachment.read.

Python
Node.js

import os

for invoice in invoices:
    if not invoice.get("attachment_id"):
        continue

    attachment_response = requests.get(
        f"{BASE_URL}/attachments/{invoice['attachment_id']}",
        headers=headers,
    )
    attachment_response.raise_for_status()
    attachment = attachment_response.json()["attachment"]

    file_response = requests.get(attachment["url"])
    file_response.raise_for_status()

    os.makedirs("./supplier_invoices", exist_ok=True)
    with open(f"./supplier_invoices/{attachment['file_name']}", "wb") as f:
        f.write(file_response.content)

    print(f"Downloaded: {attachment['file_name']}")

import { writeFile, mkdir } from "node:fs/promises";

for (const invoice of invoices) {
  if (!invoice.attachment_id) continue;

  const attachmentResponse = await fetch(
    `${BASE_URL}/attachments/${invoice.attachment_id}`,
    { headers }
  );
  if (!attachmentResponse.ok) throw new Error(`HTTP ${attachmentResponse.status}`);

  const { attachment } = await attachmentResponse.json();

  const fileResponse = await fetch(attachment.url);
  await mkdir("./supplier_invoices", { recursive: true });
  const buffer = Buffer.from(await fileResponse.arrayBuffer());
  await writeFile(`./supplier_invoices/${attachment.file_name}`, buffer);

  console.log(`Downloaded: ${attachment.file_name}`);
}

Store the sync timestamp

Persist the new sync timestamp only after full success.

Python
Node.js

save_to_db("last_supplier_invoice_sync_at", current_sync_at) # Use your own tools here
print(f"Sync complete. Next run will start from: {current_sync_at}")

await saveToDB("last_supplier_invoice_sync_at", currentSyncAt); // Use your own tools here
console.log(`Sync complete. Next run will start from: ${currentSyncAt}`);

Example output:

[Step 1] Initialize sync timestamps
  lastSyncAt:    2026-03-18T00:00:00Z
  currentSyncAt: 2026-03-19T16:50:12.227Z

[Step 2] GET /supplier_invoices (paginated)
  Fetched 2 supplier invoices

[Step 3] Download attachments
  Downloaded: supplier_invoice_1.pdf
  Downloaded: supplier_invoice_2.pdf

[Step 4] Store sync timestamp
  Sync complete. Next run will start from: 2026-03-19T16:50:12.22

We now have an up-to-date local copy of all supplier invoices and their attachments for the given time window.

Documentation Index

Initialize the sync timestamp

Fetch all supplier invoices updated in the time window

Retrieve and download attachments

Store the sync timestamp