The API is the product.
Five calls from an empty organization to the first compliant invoice. One data model for finance, engineering and ops: documented, versioned, replay-safe.
Five calls to the first invoice.
No setup wizard, no console clicking. Everything Kontorion can do is an API call. This is the shortest path.
- 01
customer.createdCreate the customer
With a VAT ID, the VIES check runs automatically.
terminalcurl -X POST https://api.kontorion.eu/v1/customers \ -d name="Acme GmbH" -d country="DE" \ -d vat_id="DE123456789"→ 201 · customer.created · vies: valid
- 02
product.createdDefine the product
Defined once, billable everywhere, with a metric for usage.
terminalcurl -X POST https://api.kontorion.eu/v1/products \ -d name="API Platform" -d metric="api_calls"→ 201 · product.created
- 03
plan.createdPlan with graduated pricing
VOLUME, STAIRCASE or PACKAGE, versioned from day one.
terminalcurl -X POST https://api.kontorion.eu/v1/plans \ -d product="prod_x1" -d model="STAIRCASE" \ -d tiers[0][up_to]=50000 -d tiers[0][rate]="0.008"→ 201 · plan.created · pinned @v1
- 04
subscription.activatedStart the subscription
Trial, proration and SEPA mandate included.
terminalcurl -X POST https://api.kontorion.eu/v1/subscriptions \ -d customer="cus_8f2k" -d plan="plan_pro@v1" \ -d trial_days=14→ 201 · subscription.activated
- 05
invoice.createdThe first invoice
Jump forward with a test clock: the invoice is produced exactly as in production.
terminalcurl -X POST https://api.kontorion.eu/v1/test_clocks/tc_1/advance \ -d to="2026-05-01"→ invoice.created · XRechnung valid · € 412,80
What the API guarantees.
Commitments, not a feature list: what every response, every error and every webhook is bound to honor.
Signed, at-least-once, replayable.
Every event carries an HMAC signature and a unique ID. Delivery retries until your endpoint confirms. Duplicates are detected by event ID.
RFC 9457 Problem Details.
Every error is machine-readable: type, title, status, detail. No guessing, no parsing error strings with regex.
Every POST, safely repeatable.
The Idempotency-Key header deduplicates retries, so network failures never create double bookings.
Cursors, not offsets.
Stable under load, consistent with concurrent inserts, built for exports and syncs.
Fast-forward time in the sandbox.
Trials, renewals, dunning runs: deterministically testable before real money moves.
plan@v3, forever.
Subscriptions pin their plan version. Catalog changes never mutate live invoices.
The spec is the contract.
Every endpoint, every schema, every error code lives in the machine-readable spec, client generation included.
An index machines can read.
At /llms.txt the whole docs corpus sits as a flat list: every entry a link with one line of context. Generated from the real docs sitemap, so only pages that actually exist appear.
Full docs index: https://docs.kontorion.eu/llms.txt A .md variant per page
Every docs page also as plain Markdown at the same URL with .md, token-efficient for agents. In preparation, not yet live everywhere.
# Kontorion
> EU-native billing infrastructure. Machine-readable index of the docs.
## Docs
- [Create customers](https://docs.kontorion.eu/customers.md): Create a customer with VAT ID and automatic VIES check.- [Define products](https://docs.kontorion.eu/products.md): A billable unit with a usage metric.- [Plans & graduated pricing](https://docs.kontorion.eu/plans.md): VOLUME, STAIRCASE or PACKAGE, versioned from day one.- [Subscriptions](https://docs.kontorion.eu/subscriptions.md): Trial, proration and SEPA mandate included.- [Invoices](https://docs.kontorion.eu/invoices.md): XRechnung and ZUGFeRD, validated before dispatch.- [Webhooks](https://docs.kontorion.eu/webhooks.md): HMAC-signed, at-least-once, replay-safe.- [Test clocks](https://docs.kontorion.eu/test-clocks.md): Advance sandbox time deterministically. ## OpenAPI
- [OpenAPI 3.0](https://docs.kontorion.eu/v1/openapi.json): The specification is the contract: client generation included. # Updated: 2026-07-04 · generated from the docs sitemapEverything else lives in the reference.
Complete endpoints, schemas, webhook catalogs and examples, readable without signing up, instantly usable with sandbox keys. And anywhere on this site, pressing i reveals each artifact's API path, including right here.