Kundenschreiber Public API

Name: Kundenschreiber Public API API
Brand: Kundenschreiber Public API
Availability: InStock

★ Only Publicly Available OpenAPI DocumentMarketingMarketing AutomationapiKey33 EndpointsREST

For Agents

Send handwritten letters and postcards via Kundenschreiber: create orders, manage senders and recipients, run trackable QR campaigns, and check shipment credits.

Connect the Kundenschreiber Public API to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Kundenschreiber Public API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.

Install Jentic One Beta (Self-Hosted)

Jentic One Host machine

# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh

Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register       # connects your agent to your Jentic One instance

Jentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.

Capabilities

What an agent can do with Kundenschreiber Public API API.

Place handwritten-letter and postcard orders via POST /orders against pre-built templates from /templates

Check available shipment credit before sending via GET /shipment-balance to avoid failed dispatch

Run trackable direct-mail QR campaigns through /qr/campaigns and /qr/codes for response attribution

Manage sender and recipient address books via /senders and /recipients with create, update, and delete

GET STARTED

Start building with Kundenschreiber Public API API

Explore with Jentic

View OpenAPI Document

Jentic publishes the only available OpenAPI document for Kundenschreiber Public API, keeping it validated and agent-ready.

Jentic publishes the only available OpenAPI specification for Kundenschreiber Public API, keeping it validated and agent-ready. Kundenschreiber is a German handwritten-letter and postcard service whose API lets businesses create direct-mail orders, manage senders and recipients, run QR campaigns with trackable codes, and enrich company data before mailing. Authentication is an X-API-Key header. Endpoints cover the full direct-mail workflow from credit-balance checks to template selection, signature variations, and order placement.

Use Cases

Patterns agents use Kundenschreiber Public API API for, with concrete tasks.

★ Automated Customer Win-Back Letters

Trigger handwritten letters to lapsed customers as part of a churn-recovery flow. After a CRM identifies a churn-risk segment, an agent uploads the recipient list to /recipients, picks a win-back template via /templates, and POSTs the order to /orders. /shipment-balance is checked first so the run doesn't fail mid-batch.

GET /shipment-balance, GET /templates to pick the 'win-back' template, POST 50 recipients to /recipients, then POST /orders referencing the template and recipient IDs.

QR-Tracked Postcard Campaigns

Run a postcard campaign with QR codes that link each recipient to a tracked landing page. POST /qr/campaigns creates the campaign, POST /qr/codes generates per-recipient codes, and the postcard order references those codes so recipients scanning the postcard are attributed to the campaign in analytics.

POST /qr/campaigns with a campaign name, generate one QR code per recipient via /qr/codes, and submit a postcard order to /orders with the QR codes embedded.

Multi-Signature Brand Templates

Maintain different signature variations for different sales reps so handwritten letters carry the right rep's signature. /signatures lists existing variations, PATCH /signatures/{id} updates them, and orders pick the right signature at send time. This keeps personalisation high without re-creating templates.

GET /signatures, pick the rep's variation, and POST /orders with the chosen signature ID for each recipient.

AI Agent Direct-Mail Concierge

An assistant in a sales-ops chat receives instructions like 'send a handwritten thank-you to every closed-won deal this week' and runs the full Kundenschreiber order through Jentic. Search-by-intent finds the right operation, schemas are loaded automatically, and the X-API-Key never leaves the vault.

On 'thank every closed-won deal this week', resolve recipient list from CRM, search Jentic for 'create Kundenschreiber order', and POST /orders with the thank-you template ID.

Key Endpoints

33 endpoints — jentic publishes the only available openapi specification for kundenschreiber public api, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/orders

Create a handwritten letter or postcard order

GET

/shipment-balance

Check shipment credit balance

GET

/templates

List letter templates

POST

/qr/campaigns

Create a trackable QR campaign

POST

/recipients

Add a recipient to the address book

POST

/enrich-company

Enrich company data before mailing

POST

/orders

Create a handwritten letter or postcard order

GET

/shipment-balance

Check shipment credit balance

GET

/templates

List letter templates

POST

/qr/campaigns

Create a trackable QR campaign

POST

/recipients

Add a recipient to the address book

Why though Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

Kundenschreiber X-API-Key values are stored encrypted in the Jentic MAXsystem vault. The header is injected at execution time so the agent context never holds the raw key.

Intent-based discovery

Agents search by intent (e.g. 'send a handwritten letter' or 'create a QR campaign') and Jentic returns the matching Kundenschreiber operation with its input schema.

Time to first call

Direct integration: 1 day for auth, address book modelling, and template selection. Through Jentic: under 30 minutes — search, load, execute.

Related APIs

Alternatives and complements available in the Jentic catalogue.

Alternative

Lettermint API

Direct-mail API for letters and postcards with a similar workflow.

Choose Lettermint when sending mail outside Kundenschreiber's primary German-speaking coverage.

Alternative

Postal Server API

Self-hosted mail server for transactional email — different channel.

Use Postal Server when the goal is transactional email rather than physical mail.

Complementary

Clearbit API

Company-data enrichment for personalising direct mail.

Use Clearbit when /enrich-company isn't enough and the campaign needs deeper firmographic data.

FAQs

Specific to using Kundenschreiber Public API API through Jentic.

Why is there no official OpenAPI spec for Kundenschreiber Public API?

Kundenschreiber does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Kundenschreiber Public API via structured tooling. It is validated against the live API and kept up to date. Get started at https://app.jentic.com/sign-up.

What authentication does the Kundenschreiber Public API use?

Kundenschreiber uses an API key passed in the X-API-Key header. Through Jentic, the API key is stored encrypted in the MAXsystem vault and injected at request time so the agent never holds the raw secret.

Can I send a handwritten letter to a recipient with the Kundenschreiber API?

Yes. POST /orders creates a handwritten letter or postcard order against a template ID from /templates and a recipient ID from /recipients. Check /shipment-balance first to confirm the account has credits for the run.

How do I run a QR-tracked direct-mail campaign through Jentic?

Search Jentic for 'create a Kundenschreiber QR campaign'. Jentic returns POST /qr/campaigns and POST /qr/codes. Generate one code per recipient, then POST /orders with the codes referenced on each piece.

What are the rate limits for the Kundenschreiber Public API?

Specific rate limits are not exposed in the public OpenAPI spec. Contact support@kundenschreiber.de to confirm per-account limits before scheduling large batches.

Can I enrich company data before sending a letter?

Yes. POST /enrich-company augments a company record before personalisation, so letters can address recipients by their current company details. Use this before constructing the order body.