What you can build

Start with one invoice call and one signed webhook. Add payment links, reminders or collection only when your product needs them.

1Send the invoice
POST /v1/invoices
Rieck creates the PDF, issues the invoice and delivers it to the customer.
Invoice flow
2Receive the result
invoice.paid
A signed webhook keeps your order, ledger or customer access in sync.
Webhook handling
3Recover overdue debt
POST /v1/invoices/{id}/collect
Continue into reminders and collection without building another customer flow.
Collection flow

Customer experience

Your API call becomes something the customer can use

Rieck hosts the secure customer surface. The customer can pay, request an instalment plan, object to the claim and open the documents behind the case.

Rieck customer portal showing payment, instalment plan, objection and document options for a collection case — **Hosted customer portal** Responsive, secure and connected to the case

Built by you: The trigger and your business rules
Handled by Rieck: Documents, payment and statutory workflow
Returned to you: Signed status events

Choose the smallest integration

Your goal	Start with	Add when needed
Send an invoice and get paid	`POST /v1/invoices?issue=true&send=true`	`invoice.paid` webhook
Add payments to your own UI	`POST /v1/invoices/{id}/payment-link`	Hosted customer portal
Gate a SaaS account on unpaid debt	`GET /v1/customers/{id}/balance`	`customer.past_due` webhook
Automate recurring billing	`POST /v1/subscriptions`	Payment-method setup link
Continue an overdue invoice into collection	`POST /v1/invoices/{id}/collect`	Case status and event feed

The integration cookbook describes the recommended shape for webshops, SaaS products, ERPs and accounting systems.