FBR Digital Invoicing — PRAL Integrator (Pakistan)

FBR Digital Invoicing is a production-ready, compliance-grade digital invoicing system built for Pakistani businesses required to integrate with the Federal Board of Revenue's Digital Invoicing (DI) API via the PRAL gateway. The system is built with a vanilla JavaScript + HTML5 frontend and a framework-less PHP REST API backend, backed by MySQL 8, containerised with Docker Compose for one-command deployment.

The system handles the complete FBR DI invoicing lifecycle: seller profile management (NTN/CNIC, business name, province), buyer registration (CNIC/NTN/STRN, registration type, address), product/service catalog with HS codes, unit of measure, rate, and optional SRO fields, and full invoice creation with dynamic line items and real-time calculations.

Compliance is enforced at the code level — the DI JSON generator uses a strict allowlist extracted directly from the official FBR DI API PDF specification, rejecting any missing required fields and including no non-spec fields. Both validate (validateinvoicedata_sb) and submit (postinvoicedata) PRAL endpoints are implemented, with mock mode returning realistic DI-like responses for testing without external calls, and live mode calling PRAL with a securely stored, AES-encrypted Bearer token.

Each invoice generates a QR code containing the IRN (Invoice Reference Number) and supports both browser print view and server-generated PDF download. All PRAL API requests and responses are logged in fbr_api_logs with full audit trails in audit_logs, providing the compliance paper trail required for FBR inspection. Invoices are locked non-editable after submission attempt, matching FBR requirements. Security is handled via opaque Bearer tokens stored hashed in the database, with environment-based configuration for all secrets.