For ERP, industry software and SaaS

E-invoices that pass every check. Through an API.

One JSON call returns a calculated XRechnung (UBL or CII) and ZUGFeRD, checked with the KoSIT validator.

Try free for 30 days Read the documentation

20 test invoices, no payment details. OpenAPI description to download.

For management and product
Build or integrate? The business case at a glance

# sellerId: ID of your seller from the portal
curl -X POST https://api.fakturnaut.com/v1/invoices \
  -H "Authorization: Bearer $FAKTURNAUT_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen 2>/dev/null || cat /proc/sys/kernel/random/uuid)" \
  --data @- <<'JSON'
{
  "sellerId": "5b1d7f0e-3c2a-4e8b-9f61-2d4c8a7e9b03",
  "number": "RE-2026-0042",
  "issueDate": "2026-11-02",
  "dueDate": "2026-12-02",
  "buyerReference": "PO-4711",
  "buyer": {
    "name": "Muster GmbH",
    "electronicAddress": "rechnung@muster-gmbh.example",
    "electronicAddressScheme": "EM",
    "address": {
      "street": "Musterstraße 1",
      "city": "Berlin",
      "postCode": "10115",
      "country": "DE"
    }
  },
  "lines": [
    {
      "name": "Softwarelizenz November",
      "quantity": 1,
      "unitCode": "C62",
      "netPrice": 490,
      "vatRate": 19
    },
    {
      "name": "Einrichtung",
      "quantity": 4,
      "unitCode": "HUR",
      "netPrice": 95,
      "vatRate": 19
    }
  ]
}
JSON

// sellerId: ID of your seller from the portal
const invoice = {
  "sellerId": "5b1d7f0e-3c2a-4e8b-9f61-2d4c8a7e9b03",
  "number": "RE-2026-0042",
  "issueDate": "2026-11-02",
  "dueDate": "2026-12-02",
  "buyerReference": "PO-4711",
  "buyer": {
    "name": "Muster GmbH",
    "electronicAddress": "rechnung@muster-gmbh.example",
    "electronicAddressScheme": "EM",
    "address": {
      "street": "Musterstraße 1",
      "city": "Berlin",
      "postCode": "10115",
      "country": "DE"
    }
  },
  "lines": [
    {
      "name": "Softwarelizenz November",
      "quantity": 1,
      "unitCode": "C62",
      "netPrice": 490,
      "vatRate": 19
    },
    {
      "name": "Einrichtung",
      "quantity": 4,
      "unitCode": "HUR",
      "netPrice": 95,
      "vatRate": 19
    }
  ]
};

const response = await fetch('https://api.fakturnaut.com/v1/invoices', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.FAKTURNAUT_KEY}`, // fkn_test_…
    'Content-Type': 'application/json',
    'Idempotency-Key': crypto.randomUUID(),
  },
  body: JSON.stringify(invoice),
});
const issued = await response.json();

<?php
// sellerId: ID of your seller from the portal
$invoice = <<<'JSON'
{
  "sellerId": "5b1d7f0e-3c2a-4e8b-9f61-2d4c8a7e9b03",
  "number": "RE-2026-0042",
  "issueDate": "2026-11-02",
  "dueDate": "2026-12-02",
  "buyerReference": "PO-4711",
  "buyer": {
    "name": "Muster GmbH",
    "electronicAddress": "rechnung@muster-gmbh.example",
    "electronicAddressScheme": "EM",
    "address": {
      "street": "Musterstraße 1",
      "city": "Berlin",
      "postCode": "10115",
      "country": "DE"
    }
  },
  "lines": [
    {
      "name": "Softwarelizenz November",
      "quantity": 1,
      "unitCode": "C62",
      "netPrice": 490,
      "vatRate": 19
    },
    {
      "name": "Einrichtung",
      "quantity": 4,
      "unitCode": "HUR",
      "netPrice": 95,
      "vatRate": 19
    }
  ]
}
JSON;

$ch = curl_init('https://api.fakturnaut.com/v1/invoices');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer ' . getenv('FAKTURNAUT_KEY'), // fkn_test_…
        'Content-Type: application/json',
        'Idempotency-Key: ' . bin2hex(random_bytes(16)),
    ],
    CURLOPT_POSTFIELDS => $invoice,
]);
$issued = json_decode(curl_exec($ch), true);

// sellerId: ID of your seller from the portal
String invoice = """
    {
      "sellerId": "5b1d7f0e-3c2a-4e8b-9f61-2d4c8a7e9b03",
      "number": "RE-2026-0042",
      "issueDate": "2026-11-02",
      "dueDate": "2026-12-02",
      "buyerReference": "PO-4711",
      "buyer": {
        "name": "Muster GmbH",
        "electronicAddress": "rechnung@muster-gmbh.example",
        "electronicAddressScheme": "EM",
        "address": {
          "street": "Musterstraße 1",
          "city": "Berlin",
          "postCode": "10115",
          "country": "DE"
        }
      },
      "lines": [
        {
          "name": "Softwarelizenz November",
          "quantity": 1,
          "unitCode": "C62",
          "netPrice": 490,
          "vatRate": 19
        },
        {
          "name": "Einrichtung",
          "quantity": 4,
          "unitCode": "HUR",
          "netPrice": 95,
          "vatRate": 19
        }
      ]
    }
    """;

HttpRequest request = HttpRequest.newBuilder(URI.create("https://api.fakturnaut.com/v1/invoices"))
    .header("Authorization", "Bearer " + System.getenv("FAKTURNAUT_KEY")) // fkn_test_…
    .header("Content-Type", "application/json")
    .header("Idempotency-Key", UUID.randomUUID().toString())
    .POST(HttpRequest.BodyPublishers.ofString(invoice))
    .build();
HttpResponse<String> issued = HttpClient.newHttpClient()
    .send(request, HttpResponse.BodyHandlers.ofString());

// sellerId: ID of your seller from the portal
var invoice = """
    {
      "sellerId": "5b1d7f0e-3c2a-4e8b-9f61-2d4c8a7e9b03",
      "number": "RE-2026-0042",
      "issueDate": "2026-11-02",
      "dueDate": "2026-12-02",
      "buyerReference": "PO-4711",
      "buyer": {
        "name": "Muster GmbH",
        "electronicAddress": "rechnung@muster-gmbh.example",
        "electronicAddressScheme": "EM",
        "address": {
          "street": "Musterstraße 1",
          "city": "Berlin",
          "postCode": "10115",
          "country": "DE"
        }
      },
      "lines": [
        {
          "name": "Softwarelizenz November",
          "quantity": 1,
          "unitCode": "C62",
          "netPrice": 490,
          "vatRate": 19
        },
        {
          "name": "Einrichtung",
          "quantity": 4,
          "unitCode": "HUR",
          "netPrice": 95,
          "vatRate": 19
        }
      ]
    }
    """;

using var request = new HttpRequestMessage(HttpMethod.Post, "https://api.fakturnaut.com/v1/invoices")
{
    Content = new StringContent(invoice, Encoding.UTF8, "application/json"),
};
request.Headers.Authorization = new AuthenticationHeaderValue(
    "Bearer", Environment.GetEnvironmentVariable("FAKTURNAUT_KEY")); // fkn_test_…
// A new key per invoice; reuse it only when you retry this request.
request.Headers.Add("Idempotency-Key", Guid.NewGuid().ToString());
var issued = await http.SendAsync(request); // http: your shared HttpClient

{
  "id": "0c9e6a52-71f4-4b8d-a3e2-6f5d9b1c2e47",
  "number": "RE-2026-0042",
  "typeCode": "380",
  "amountDue": 1035.3,
  "currency": "EUR",
  "findings": [],
  "documents": [
    {
      "format": "xrechnung-ubl",
      "href": "/v1/invoices/0c9e6a52-71f4-4b8d-a3e2-6f5d9b1c2e47/document?format=xrechnung-ubl"
    },
    {
      "format": "zugferd",
      "href": "/v1/invoices/0c9e6a52-71f4-4b8d-a3e2-6f5d9b1c2e47/document?format=zugferd"
    }
  ]
}

EN 16931
XRechnung UBL
XRechnung CII
ZUGFeRD
Peppol
KoSIT-Validator
OpenAPI
Servers in Frankfurt
DE · RO

For developers

One call, three steps, no standards to read

POST /v1/invoices
Send the invoice as JSON
Seller, buyer, lines, tax rates. With an Idempotency-Key, so a retry never issues twice.
findings: []
Calculated and checked
Totals and VAT under EN 16931. Every invoice goes through the KoSIT validator; deviations come back as findings.
documents · webhooks
Deliver
Fetch XRechnung UBL/CII and ZUGFeRD, deliver over Peppol, hear about every status change by webhook.

For management and product

Solve your customers' e-invoicing mandate without in-house standards know-how.

On the market in time
Your customers must issue e-invoices from 1 January 2027 or 2028. You connect an interface instead of starting a standards project.
Less risk
Every invoice is checked with the official KoSIT validator before it goes out. The rules of the standard live in Fakturnaut, not in your code.
Predictable costs
From €49 a month for 250 invoices, billed monthly or yearly. No project budget.

Build or integrate?

Task	Build it yourself	With Fakturnaut
Understand EN 16931 and XRechnung	Your team learns the standard	Built into the API
Create three formats	Build and maintain UBL, CII and the ZUGFeRD PDF	One JSON call
Official check	Integrate and run the KoSIT validator yourself	Included with every invoice
Delivery	E-mail sending and a Peppol connection	Peppol included in Growth, Scale and Enterprise
Several clients	Your own data model for sellers	Several sellers per account
Changes to the standard	Permanently in your own backlog	Normative XRechnung releases: live within 4 weeks of the final KoSIT bundle, and always before they take effect. Code list updates within 2 weeks. ZUGFeRD: within 4 weeks of the FeRD release. Running 3.0 and 4.0 side by side during the transition period is included.
Cost	About 30–60 developer days once to move to XRechnung 4.0 / EN 16931-1:2026, then about 15–25 days a year for 4–6 releases and monitoring, plus running the validator. At €800 a day: about €24k–48k once plus €13k–21k a year.	from €49 a month

See pricing Book a call

For developers

What the API brings

OpenAPI description
Generate clients instead of typing them. Examples in curl, TypeScript, PHP, Java and C#.
Idempotent calls
The same Idempotency-Key never issues an invoice twice.
Webhooks
Your system learns about delivery and status changes without polling.
Several sellers
Each of your customers is a seller with its own sellerId, all in one account.
Peppol
Via Peppol on the Growth, Scale and Enterprise plans. Sending by e-mail: in preparation. Germany and Romania are supported today.
Run in Frankfurt
Servers in the EU, a public status page.
Self-billing (Gutschriften): in preparation
Access on request: write to us.

Prefer an SDK? There are SDKs for TypeScript, PHP, Java and C#. Guide: create an XRechnung via API

Pricing by invoices issued

Try free for 30 days: 20 test invoices, no payment details, ends by itself.

StarterTo start

€49a month, net

To get started.

250 invoices a month
arithmetically €0.20 per invoice
XRechnung UBL/CII and ZUGFeRD
Unlimited checking
Peppol in test only
Sellers in Germany

Try 30 days

Growth

€249a month, net

For growing numbers of customers.

2,500 invoices a month
arithmetically €0.10 per invoice
XRechnung UBL/CII and ZUGFeRD
Unlimited checking
Delivery over Peppol

Try 30 days

Scale

€749a month, net

For large invoice volumes.

15,000 invoices a month
arithmetically €0.05 per invoice
XRechnung UBL/CII and ZUGFeRD
Unlimited checking
Delivery over Peppol
Target: 99.9% availability

Try 30 days

Enterprise

from €1,500a month, net

By agreement.

More than 15,000 invoices
Payment by invoice

Get in touch

The price depends on the invoices issued and the active sellers per month. Checking is unlimited on every plan. All pricing details

All prices are net in euros plus statutory VAT. Paid plans are billed monthly or yearly, by card or SEPA Direct Debit through Stripe; Enterprise by invoice, by agreement. Monthly terms can be cancelled every month, yearly terms at their end.

The price list and the terms are binding.

Only writing your own invoices? The app starts at €0.

GoBD: what Fakturnaut covers

What Fakturnaut covers

Stored invoices cannot be changed and are secured with a checksum.
Corrections only through corrective invoices.

As a business you remain responsible for retention and your procedure documentation. Not tax or legal advice.

Sources: Section 147 AO · Section 14b UStG. Not tax or legal advice.

Frequently asked questions

Is there a sandbox?

Yes. The trial runs 30 days with up to 20 test invoices and needs no payment details. The invoices carry the note "TESTRECHNUNG"; Peppol is simulated in the test.

Sources: Sandbox

Do I have to rebuild my software?

No. Your software sends the invoice data as JSON to our API. We take care of format, calculation and checking, and of sending if you want.

Sources: Quickstart

What happens with a duplicate call?

With the same Idempotency-Key the API does not issue a second invoice.

How do I pay?

By card or SEPA Direct Debit through Stripe; your plan is active at once. Enterprise customers pay by invoice as agreed.

Sources: Terms

Which formats does the API create?

XRechnung 3.0 in UBL and CII, ZUGFeRD/Factur-X in the EN 16931 profile and, for Romania, RO e-Factura. We validate every file we create with the KoSIT validator and rules.

Sources: XRechnung (KoSIT) · ZUGFeRD (FeRD)

Do I need Peppol?

Not necessarily. German law does not prescribe a transmission channel for e-invoices between businesses; e-mail is allowed too. Many public-sector buyers accept invoices via Peppol. Peppol is included on the Growth, Scale and Enterprise plans.

Sources: Questions and answers on e-invoicing (Federal Ministry of Finance) · E-invoices to the federal government (e-rechnung-bund.de)

Where are the servers?

In Frankfurt am Main in the EU. The privacy policy and the data processing agreement describe how we process data.

Sources: Privacy policy · Data processing agreement

What happens from 2027 and 2028?

Since 1 January 2025, businesses in Germany must be able to receive e-invoices. From 1 January 2027, businesses with more than €800,000 turnover in the previous year issue invoices to other domestic businesses as e-invoices; from 1 January 2028, all others do.

Sources: Section 27(38) UStG · BMF letter of 15 October 2025 · Questions and answers on e-invoicing (Federal Ministry of Finance)

Do you support self-billing?

We are preparing self-billed invoices in the sense of German VAT law (Gutschriften, invoice type 389); access is available on request. Corrections and cancellation invoices that refer to the original invoice can already be issued through the API.

Sources: Section 14 UStG

How fast is the integration?

You send your first test invoice within minutes. How long connecting your software takes depends on how your invoice data is structured; the API fields follow the EN 16931 standard.

Sources: Quickstart

Who is liable for the content of the invoice?

Whoever issues the invoice remains responsible for its content and correctness. We create the file, validate it against the technical rules and deliver it. Our terms set out the details.

Sources: Terms · Section 14 UStG

These answers are not tax or legal advice.

The first checked XRechnung from your code, today.

30 days, 20 test invoices, no payment details.

Try free for 30 days

E-invoices that pass every check. Through an API.

Response, shortened

One call, three steps, no standards to read

Send the invoice as JSON

Calculated and checked

Deliver

Solve your customers' e-invoicing mandate without in-house standards know-how.

On the market in time

Less risk

Predictable costs

Build or integrate?

What the API brings

OpenAPI description

Idempotent calls

Webhooks

Several sellers

Peppol

Run in Frankfurt

Self-billing (Gutschriften): in preparation

Pricing by invoices issued

StarterTo start

Growth

Scale

Enterprise

GoBD: what Fakturnaut covers

Frequently asked questions

The first checked XRechnung from your code, today.