DueBuddy API: send an invoice, get the fields back

In short: one endpoint takes a file and returns invoice fields as JSON: invoice number, dates, supplier, buyer, VAT ID, IBAN, BIC, net/VAT/gross amounts and currency. E-invoices (ZUGFeRD, Factur-X, XRechnung, UBL/Peppol, Swiss QR) are read from their structured data, not recognised from a picture. Scans and photos go through recognition with arithmetic and checksum checks on top.

Get an API key and start

How it works

Parsing is asynchronous because a scan takes a few seconds. You send the file, you get a job number, you ask for the result.

Step	Call
1. Send the invoice	POST /v1/parse with header X-Api-Key and the file
2. Read the result	GET /v1/parse/{job_id} until the status is done

Try it with curl

curl -X POST https://duebuddy.work/v1/parse \
  -H "X-Api-Key: YOUR_KEY" \
  -F "[email protected]"

# → {"ok":true,"job_id":123,"status":"processing"}

curl https://duebuddy.work/v1/parse/123 \
  -H "X-Api-Key: YOUR_KEY"

Or with Python (standard library only)

No dependencies to install. Works on a server or a laptop.

import json, pathlib, time, urllib.request, uuid

API_KEY = "YOUR_KEY"
BASE = "https://app.duebuddy.work"

def parse(path):
    data = pathlib.Path(path).read_bytes()
    boundary = uuid.uuid4().hex
    body = (f'--{boundary}\r\n'
            f'Content-Disposition: form-data; name="file"; filename="{pathlib.Path(path).name}"\r\n'
            f'Content-Type: application/pdf\r\n\r\n').encode() + data + f"\r\n--{boundary}--\r\n".encode()
    req = urllib.request.Request(f"{BASE}/v1/parse", data=body, method="POST",
        headers={"X-Api-Key": API_KEY,
                 "Content-Type": f"multipart/form-data; boundary={boundary}"})
    job = json.load(urllib.request.urlopen(req))["job_id"]
    while True:
        time.sleep(3)
        r = urllib.request.Request(f"{BASE}/v1/parse/{job}", headers={"X-Api-Key": API_KEY})
        out = json.load(urllib.request.urlopen(r))
        if out.get("status") in ("done", "failed"):
            return out

print(parse("invoice.pdf")["fields"])

What you get back

{
  "status": "done",
  "fields": {
    "invoice_no": "R0005532486",
    "invoice_date": "19.01.2016",
    "due_date": "22.01.2016",
    "currency": "EUR",
    "seller_name": "Hetzner Online GmbH",
    "seller_address": "Industriestr. 25, 91710 Gunzenhausen",
    "seller_vat_id": "DE812871812",
    "seller_iban": "DE92760700120750007700",
    "seller_bic": "DEUTDEMM760",
    "buyer_name": "Usegroup Inh. Jochen Stärk",
    "gross_amount": "104.00"
  }
}

Fields we could not confirm stay empty and are marked. The system does not invent values: if the arithmetic does not add up or an IBAN fails its checksum, the field is flagged instead of guessed. The the same file is deduplicated by content hash and is not charged twice.

Supported input

Format	How it is read
ZUGFeRD, Factur-X, XRechnung, UBL/Peppol	Read from the embedded XML
Swiss QR bill, SEPA QR (GiroCode)	Read from the QR code
PDF with a text layer	Read from the text layer
Scan or photo (PDF, JPG, PNG)	Recognition plus checks

Price

EUR 0.07 per scanned page. You pay for recognising an image — a scan, a photo, a screenshot. Invoices that already carry their data in code (ZUGFeRD, XRechnung, UBL, FatturaPA, QR) are read free and without limit.

Minimum top-up: EUR 8 — one month of use. The first 5 scanned pages are free, no card required. Web Beta and API usage are billed separately: the Beta allowance applies to the web app, in the API the first 5 scanned pages are free. The same file is deduplicated by content hash and is never charged twice.

For reference, published prices of comparable services run from about $0.05 (Mindee) to $1.80 (Nanonets) per document. We sit in the middle and are honest that the cheapest competitor is cheaper on paper.

Get a key

The key is issued in the dashboard. Sign up, pick the parsing plan, and the key appears there. Paste it into the header X-Api-Key and you are running.

Get an API key

What the API does not do

It does not create invoices, does not post to accounting accounts, and does not give tax advice. It reads incoming invoices and returns the field values. What you do with them is your system's job.

Status: 5 October 2026. Questions about rate limits and larger volumes: ask before you build, so we can tell you what the current setup handles.