Automated Billing System

Every credit top-up triggers an automated billing workflow: a PDF proforma invoice is generated, signed with the company details, and delivered to the customer's inbox — without any human intervention.

Technical implementation

• WeasyPrint renders HTML invoice templates to PDF with pixel-perfect layout
• Async SMTP delivers via Gmail relay with attachment support
• Invoice numbers are sequential and stored in Postgres for accounting compliance
• LiteLLM callbacks fire the invoice workflow on successful payment events

Compliance

Invoices include VAT, Italian fiscal details, and are formatted to Italian invoicing standards (fattura proforma). The system handles the full lifecycle: creation, delivery, and audit trail — all within the EU data boundary.

Payment event → litellm_callback → receipt.py → PDF render → SMTP → customer inbox