API documentation

Base URL: https://fakturwire.com · Auth: Authorization: Bearer fw_live_… · Every new account gets 50 free credits — no card required. 

# 1. Sign up → API key + 50 free credits
curl -X POST https://fakturwire.com/v1/signup \
  -H 'content-type: application/json' \
  -d '{"email":"you@example.com"}'

# 2. Convert JSON → XRechnung (2 credits)
curl -X POST https://fakturwire.com/v1/convert \
  -H "authorization: Bearer $FW_KEY" \
  -H 'content-type: application/json' \
  -d '{"target":"xrechnung-ubl","invoice":<INVOICE_JSON>}'
const res = await fetch('https://fakturwire.com/v1/convert', {
  method: 'POST',
  headers: {
    authorization: `Bearer ${process.env.FW_KEY}`,
    'content-type': 'application/json',
  },
  body: JSON.stringify({ target: 'xrechnung-ubl', invoice }),
});
const { xml, credits, warnings } = await res.json();
// res.status 422 → body.findings lists every rule violation
$ch = curl_init('https://fakturwire.com/v1/convert');
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_HTTPHEADER => [
    'authorization: Bearer ' . getenv('FW_KEY'),
    'content-type: application/json',
  ],
  CURLOPT_POSTFIELDS => json_encode([
    'target' => 'xrechnung-ubl',
    'invoice' => $invoice,
  ]),
]);
$result = json_decode(curl_exec($ch), true);
// $result['xml'] contains the compliant XRechnung document
import os, requests

res = requests.post(
    "https://fakturwire.com/v1/convert",
    headers={"authorization": f"Bearer {os.environ['FW_KEY']}"},
    json={"target": "xrechnung-ubl", "invoice": invoice},
)
if res.status_code == 422:
    for f in res.json()["findings"]:
        print(f["rule"], f["message"])
else:
    xml = res.json()["xml"]
using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization =
    new AuthenticationHeaderValue("Bearer", Environment.GetEnvironmentVariable("FW_KEY"));

var payload = new { target = "xrechnung-ubl", invoice };
var res = await http.PostAsJsonAsync("https://fakturwire.com/v1/convert", payload);
var body = await res.Content.ReadFromJsonAsync<JsonElement>();
// body.GetProperty("xml") → compliant XRechnung document

Official SDKs

Thin, dependency-free clients around /v1/validate, /v1/convert and /v1/me — typed errors, and 422 gives you the findings list to fix. 

# Node.js / TypeScript (npm: fakturwire)
npm install fakturwire

# PHP (Packagist: fakturwire/sdk) — coming soon
# .NET (NuGet: FakturWire) — coming soon

The Node SDK is live now. The PHP and .NET packages are built and tested — publishing shortly. Until then, call the REST API directly with the samples above.

Endpoints

POST /v1/validate — 1 credit

Body: { "xml": "<UBL string>" } or { "invoice": {…canonical JSON…} }, plus optional "profile": en16931 (default) · peppol-bis-3 · xrechnung. Returns valid, findings[] (rule, severity, message, path) and counts.

POST /v1/convert — 2 credits

Body: input (invoice JSON or xml UBL) + "target": peppol-bis-3 · xrechnung-ubl · facturx-en16931. Returns the compliant XML. If the invoice violates the target profile's rules you get HTTP 422 with the full findings list and no charge.

POST /v1/extract — 10 credits soon

PDF invoice in → structured EN 16931 JSON out (LLM-powered extraction with confidence scores), ready to pipe into /v1/convert.

GET /v1/me — free

Returns your account and current credit balance.

The canonical invoice JSON

Field names map 1:1 to EN 16931 business terms (BT-x). Amounts are strings to avoid floating-point surprises. Totals and VAT breakdown are computed for you when omitted. 

{
  "number": "INV-2026-0042",
  "issueDate": "2026-07-01",
  "dueDate": "2026-07-31",
  "currency": "EUR",
  "buyerReference": "04011000-12345-67",
  "seller": {
    "name": "Example Kft.",
    "vatId": "HU12345678",
    "electronicAddress": { "schemeId": "9910", "value": "HU12345678" },
    "address": { "streetName": "Fő utca 1.", "city": "Budapest", "postalZone": "1011", "countryCode": "HU" },
    "contact": { "name": "Anna Kovács", "phone": "+36 1 234 5678", "email": "anna@example.hu" }
  },
  "buyer": {
    "name": "Muster GmbH",
    "vatId": "DE123456789",
    "electronicAddress": { "schemeId": "9930", "value": "DE123456789" },
    "address": { "streetName": "Hauptstraße 5", "city": "Berlin", "postalZone": "10115", "countryCode": "DE" }
  },
  "payment": { "meansCode": "58", "iban": "HU42117730161111101800000000", "terms": "30 days" },
  "lines": [
    { "id": "1", "name": "Consulting", "quantity": "10", "unitCode": "HUR",
      "unitPrice": "120.00", "vat": { "categoryCode": "AE", "rate": "0" } }
  ],
  "vatBreakdown": [
    { "categoryCode": "AE", "rate": "0", "taxableAmount": "1200.00", "taxAmount": "0.00",
      "exemptionReasonCode": "VATEX-EU-AE", "exemptionReason": "Reverse charge" }
  ]
}