API

Letter API: print and mail letters to Germany and abroad

With our letter and postal API you submit PDFs straight from your software. briefsenden.com takes care of printing, enveloping and handing in at Deutsche Post for delivery in Germany and abroad. You get the processing status back into your system via API or webhook. With a test key you test without printing or sending.

API documentation Sign up for free and create a test key

Send a letter via REST API

From account to first API letter – in four simple steps

Email address

Password

Create account

Create an account

Settings → Developer

Testbv_test_••••3f9a

Livebv_live_••••c21e

Create API key

Generate an API key

Create an API key under "Settings" → "Developer". Use a test key (bv_test_*) for development or a live key (bv_live_*) for production.

cURL

POST /api/v1/letters/simple

X-Api-Key: bv_test_••••

file=@invoice.pdf

recipientLine1=Max Mustermann

recipientZip=12345

recipientCity=Berlin

201Created

Send your first letter

Send a PDF with the recipient address via POST /api/v1/letters/simple. With a test key there is no cost and no physical dispatch.

Webhook

letter.processingProcessing
letter.in_printPrinting
letter.sentSent

GET/api/v1/letters/{id}"SENT"

Query the status

Query the current shipping status via GET /api/v1/letters/{id} or get notified automatically by webhook.

One letter in one request

Send letters in your preferred programming language. Our API accepts multipart/form-data and responds with JSON.

curl -X POST https://www.briefsenden.com/api/v1/letters/simple \
  -H "X-Api-Key: bv_test_xxx" \
  -F "file=@invoice.pdf" \
  -F "recipientLine1=Max Mustermann" \
  -F "recipientLine2=Musterstraße 1" \
  -F "recipientZip=12345" \
  -F "recipientCity=Berlin" \
  -F "recipientCountry=DE" \
  -F "color=bw" \
  -F "duplex=simplex"

import requests

url = "https://www.briefsenden.com/api/v1/letters/simple"
headers = {"X-Api-Key": "bv_test_xxx"}

files = {"file": open("invoice.pdf", "rb")}
data = {
    "recipientLine1": "Max Mustermann",
    "recipientLine2": "Musterstraße 1",
    "recipientZip": "12345",
    "recipientCity": "Berlin",
    "recipientCountry": "DE",
    "color": "bw",
    "duplex": "simplex",
}

response = requests.post(url, headers=headers, files=files, data=data)
print(response.json())

// Node.js 18+, as an ES module (e.g. letter.mjs) – fetch, FormData and Blob are built in
import fs from "node:fs";

const form = new FormData();
form.append("file", new Blob([fs.readFileSync("invoice.pdf")], { type: "application/pdf" }), "invoice.pdf");
form.append("recipientLine1", "Max Mustermann");
form.append("recipientLine2", "Musterstraße 1");
form.append("recipientZip", "12345");
form.append("recipientCity", "Berlin");
form.append("recipientCountry", "DE");
form.append("color", "bw");
form.append("duplex", "simplex");

const response = await fetch("https://www.briefsenden.com/api/v1/letters/simple", {
  method: "POST",
  headers: { "X-Api-Key": "bv_test_xxx" },
  body: form,
});
console.log(await response.json());

$ch = curl_init("https://www.briefsenden.com/api/v1/letters/simple");

$postFields = [
    "file"             => new CURLFile("invoice.pdf", "application/pdf"),
    "recipientLine1"   => "Max Mustermann",
    "recipientLine2"   => "Musterstraße 1",
    "recipientZip"     => "12345",
    "recipientCity"    => "Berlin",
    "recipientCountry" => "DE",
    "color"            => "bw",
    "duplex"           => "simplex",
];

curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => $postFields,
    CURLOPT_HTTPHEADER     => ["X-Api-Key: bv_test_xxx"],
    CURLOPT_RETURNTRANSFER => true,
]);

$response = curl_exec($ch);
curl_close($ch);

echo $response;

Replace bv_test_xxx with your API key – a test key costs nothing. The full documentation with more examples is on the API documentation page.

API features

Our API follows REST principles with predictable URLs, JSON responses and standard HTTP status codes. Everything you need for a seamless integration.

RESTful JSON API

A complete REST API with OpenAPI documentation and an interactive Swagger UI. Standards-compliant JSON responses allow integration with any programming language and framework.

Test & live keys

Separate API keys for development (bv_test_*) and production (bv_live_*), sent in the X-Api-Key header. Test your integration without risk before switching to production.

Webhooks

Real-time notifications when your letters change status. Receive updates on upload, printing and dispatch automatically via HTTP callback.

Rate limiting

One request per 500 ms per API key, with a queue for up to 10 further requests. If the queue is full, the API responds with HTTP 429.

Idempotency keys

For POST requests the API stores successful responses with an idempotency key for 24 hours. Repeat the same job with the same key only after the first request has finished.

Swagger documentation

Interactive documentation with code examples and a try-it-out feature. Test endpoints right in your browser without writing a line of code.

Technical details in the API documentation: authentication, all endpoints, webhooks, error format and rate limits, letters abroad, Swagger UI.

Use cases

Companies from many industries use our API to integrate physical letter sending into their existing systems and processes.

ERP integration

Automated invoice sending straight from your ERP system. Connect your ERP via REST API or via Zapier/Make (e.g. DATEV, lexoffice) and send invoices, credit notes and receipts automatically by post.

CRM automation

Letter sending triggered by CRM events and workflows. Send welcome letters, contract documents or cancellation confirmations automatically when a CRM event fires.

Dunning systems

Automatic reminder stages with physical letters. Configure payment reminders, first and second reminders and collection notices as an automated workflow.

Document management

Integration with your DMS for automatic sending of archived documents. Trigger letter sending straight from your document management system; query the shipping status via API or receive it by webhook.

Without your own programming: Zapier, Make, n8n, DATEV & lexoffice.

Print and mail API: from PDF to letter

You submit digitally, we bring the letter on paper to Deutsche Post

1. Send a PDF
Your system sends the PDF with the recipient address to the API or has the address read from the address field of the PDF.
2. Printing and enveloping
briefsenden.com prints the letter in B/W or colour, single- or double-sided, and envelopes it.
3. Handover at Deutsche Post
The letter is franked and handed in at Deutsche Post for postal delivery in Germany or abroad. The transit time depends on the shipping type and the destination country.
4. Status in your system
Query the processing status via API or receive updates by webhook. For registered mail (Einschreiben) the tracking number is available once it has been assigned.

How much does a letter via the API cost?

A standard letter in B/W costs 91 coins, from €0.91¹ including printing, envelope and postage – via the API just as in the web interface. You top up coins in advance; there is no base fee. Calculate the cost of a letter beforehand via POST /api/v1/estimate. For recipients abroad a postage surcharge from 78 coins applies. The estimate includes it if you pass the country in country and returns the recognised country in the response.

See all prices Addressing letters abroad

¹ At the best coin rate (top-up of 25,000 coins).

Frequently asked questions

Answers about the letter API

API documentation Sign up for free and create a test key See pricing

Free test mode – no credit card needed

Integrate now

Start with a few lines of code and automate your letter sending via the REST API. Free sandbox mode included.

No base fee No minimum order Pay per letter