Chase overdue invoices without guessing the law.
Mahnwerk watches your PayPal invoices. Plain code works out when a debtor is in default, what interest and fees are owed, and which step is next (BGB 286, 288). Claude writes the letter. You read it and approve it before anything goes out.
Not legal advice. Sandbox only.
This is a hackathon demo on the PayPal sandbox. No real money moves, no real email is sent, and every debtor and invoice is fictional. Do not rely on it for a real claim.
Worked example
Invoice due 30 Sep 2026, business debtor, on 20 Nov 2026
- Principal
- €2,000.00
- Default start
- 1 Oct 2026
- Interest (10.52% = base 1.52% + 9.00%)
- €28.82
- Flat fee (BGB 288(5))
- €40.00
- Total owed
- €2,068.82
Computed live by the rules engine. Basiszinssatz 1.52% from 1 Jul 2026 (Bundesbank).
- Code decides.Default, interest, the 40 EUR flat fee and the next step, in integer cents. Tested against BGB 286 and 288.
- Claude writes.Code fills in every amount, date and citation, checks the draft, and swaps in a template if the check fails.
- You approve.Each outbound step waits in a queue until you approve it.
- PayPal sandbox sends.Invoices, reminders and simulated payments run through PayPal Invoicing. No real money moves.