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PROJECT DEEP DIVE FULL-STACK SaaS LIVE · professionalbill.com

Professional Bill:
An Invoicing SaaS With a Real Ledger

Most invoice generators are CRUD with a print button. Professional Bill is a production SaaS — double-entry accounting underneath, a GST-correct tax engine, 18 print-ready invoice skins, and an AI pipeline that reads bills and builds templates from photos.

Professional Bill — thermal invoice with UPI QR in a café

Live

Production SaaS, indexed

2×

Every entry balanced (Dr = Cr)

18

Invoice skins incl. 80mm thermal

3

AI providers orchestrated

1. A Product, Not a Demo

Professional Bill ships as a complete product with its own acquisition funnel — not a localhost demo. A marketing landing page, a no-login free invoice generator (build, preview, print, PDF — zero signup friction), an SEO-driven template gallery with per-template pages, and a blog. Sitemap, robots rules, Open Graph images and analytics are all wired in.

Free tool first

The invoice builder works without an account — the classic product-led acquisition loop.

SEO surface

Template gallery + blog + sitemap designed to rank for invoice-format queries.

Onboarding that converts

Multi-step business onboarding — GST toggle, logo/signature upload, banking — with edit-anything flows.

2. A Real Double-Entry Ledger

Every invoice save posts balanced journal entries and ledger lines against an auto-seeded 11-account chart of accounts — AR debits, revenue credits, cash/bank movements when paid, COGS and inventory moves. Debits always equal credits: correct by construction, not by convention.

Event Debit Credit
Invoice issued Accounts Receivable Revenue + Tax Payable
Payment received Cash / Bank Accounts Receivable
Stock sold Cost of Goods Sold Inventory (atomic decrement)

Tax engine: intrastate sales split into CGST + SGST, interstate sales use IGST, cess applied throughout, discounts pre-tax, per-slab summaries — plus walk-in sale mode and place-of-supply handling for India's GST rules.

3. A Guardrailed 3-Provider AI Pipeline

AI features run through three providers, each picked for its strength — with sanitization, retries, and per-user daily quotas on every endpoint:

Bill photo → invoice template

Gemini vision reads a photographed bill and returns a full template spec — business info, color theme, line-item schema — as structured JSON the app renders directly. Malicious markup and unsafe CSS are stripped before anything renders.

Messy client CSV → clean CRM

DeepSeek maps arbitrary spreadsheet headers to customer fields, skips nameless rows, and imports hundreds of clients in one upload.

Menu photo → 150 items

Vision OCR transcribes menu photos, a structuring pass reuses your existing variant labels, and sanitization caps imports at 150 validated items with GST and unit allowlists.

Professional Bill — bulk AI item import

4. Inventory Beyond CRUD

Product variants with price deltas, multi-warehouse godowns, infinite-stock mode for services, MRP/HSN/GST tracking, bulk edits — and atomic stock decrements on every sale so the ledger and the shelf never disagree.

Professional Bill — inventory management
Professional Bill — customer management

5. Built for How India Actually Bills

UPI QR codes printed on every invoice, one-tap WhatsApp sharing, Hindi invoice labels, banking with IFSC/UPI settings, and an 80mm thermal receipt skin for counter printers — the details that decide adoption with small merchants.

Professional Bill — thermal receipt with UPI QR at a café counter

Stack

Next.js 16 React 19 TypeScript Supabase Postgres Gemini Vision DeepSeek Tailwind + MUI Firebase App Hosting

Need a SaaS built like a product, not a demo?

Full-stack builds with real data models, AI integration, and SEO baked in from day one.

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