Integration cookbook

Four proven shapes — pick the one that matches your system:

Webshop / SaaS (full headless). Mirror your customers (externalReference = your id), create invoices with the one-call shortcut (POST /v1/invoices?issue=true&send=true with inline customer), subscribe to invoice.paid / customer.past_due webhooks and gate your service on GET /v1/customers/{id}/balance. Unpaid invoices flow through reminders automatically; add POST /v1/invoices/{id}/collect (or autoCollections) and the whole chain ends in debt collection without a human.

Accounting system already in place (e-conomic/Dinero/Billy). Connect it once (POST /v1/accounting-connections → human approves OAuth). Rieck pulls your invoices into the external ledger; you use the API for what accounting systems can’t do: reminders (/v1/reminder-settings), collection (/collect) and the event feed. Bookkeeping flows back to your system — no double entry.

Own ERP (invoice import). Bulk-migrate with POST /v1/batch (customers + invoices with issue: true, payments on key:index), then switch to per-event calls. Reconcile nightly with GET /v1/payments and GET /v1/settlements; catch up after downtime with GET /v1/events?since=.

Payment links only. Create issued invoices, mint links with POST /v1/invoices/{id}/payment-link (your verified payment domain brands the URL) and listen for payment.received. No portal, no e-mails from us (send omitted) — your system does the talking.