Post a letter with one request.

Your system sends text or a finished PDF, we print, envelope and post it in Germany. Idempotent via your own ID, the price is known beforehand, the delivery status can be queried.

Create account and token Full reference

Endpoints

Request	Scope	Purpose
POST/api/v1/letters/quote	letters:read	Get page count and price without sending
POST/api/v1/letters	letters:send	Typeset a letter from text (DIN 5008) and send it
POST/api/v1/letters/pdf	letters:send	Check a finished PDF and send it unchanged
GET/api/v1/letters/{id}	letters:read	Query status and delivery

How it works

Create a token under Settings → API with the scope letters:send. Tokens are shown once and stored only as a hash.

externalId makes requests idempotent: sending the same ID twice never posts a second letter.

Price per letter: €1.75 first page, +€0.75 per additional page, registered mail +€3.75. Charged from your balance.

curl -X POST https://briefdiener.de/api/v1/letters \
  -H "Authorization: Bearer bd_…" \
  -H "Content-Type: application/json" \
  -d '{
    "externalId": "mahnung-2026-0142",
    "sender":    { "company": "Muster GmbH", "address": "Hauptstr. 1\n10115 Berlin" },
    "recipient": { "name": "Max Beispiel", "address": "Lindenweg 4\n40210 Düsseldorf" },
    "subject":   "Zahlungserinnerung Rechnung 2026-0142",
    "content":   "Sehr geehrter Herr Beispiel,\n\n…",
    "registered": false
  }'

Limits

Recipients in Germany only.
Text letters carry a small Letter Manager note at the foot; PDFs are printed unchanged.
No webhooks yet: query the status.
Prepaid balance, no invoice billing.