This is a submission for the Hacktoberfest Open-Source AI Challenge Week 2: Side Hustle

What I Built

BillCraft AI is a privacy-first, intelligent invoice studio built for freelancers, contractors, and small business owners. It automates the tedious work of creating invoices and digitizing messy receipts without sending private financial data to third-party cloud servers.

The Problem It Solves

Freelancers and solopreneurs spend hours every month manually deciphering paper receipts, supplier invoices, and re-typing numbers into spreadsheets. Mainstream SaaS accounting tools charge costly monthly subscriptions ($30–$70/mo) and upload sensitive financial documents, client names, and banking details to proprietary cloud APIs.

The Solution

BillCraft AI solves this through two streamlined workflows:

1. Smart Invoice Generator: A fast workspace with persistent business profiles saved in local storage, dynamic real-time totals, one-click AI item description enhancement, and pixel-perfect branded PDF generation.
2. AI Invoice & Receipt Reader: A drag-and-drop document scanner that reads any PDF or image receipt using local OCR (RapidOCR + PyMuPDF), extracts structured line items via open-weight Qwen 2.5 7B, validates math integrity on the server, and transfers extracted data into the generator in a single click.

Freelancers, independent consultants, and micro-retailers who value financial confidentiality and want to save hours on bookkeeping would readily use and pay for this solution.

Demo

• Live Web App: https://billcraft-wzr8.onrender.com
• Local Ports: http://localhost:5173 (Frontend) | http://localhost:8000 (FastAPI Docs)

Code

• GitHub Repository: https://github.com/abhinavnayak21/BillCraft-ai-x-MLH

How I Built It

BillCraft AI is designed around open-weight models and local inference:

• Open-Weight Model: Qwen 2.5 7B (qwen2.5:7b) by Alibaba Cloud — selected for its high benchmark performance in structured JSON extraction and financial reasoning.
• Local Inference Engine: Ollama running locally on localhost:11434, ensuring 100% private, zero-latency inference.
• Cloud Fallback: For live demonstrations, the backend connects to Cloudflare Workers AI (@cf/qwen/qwen2.5-7b-instruct) for serverless, zero-cold-start inference on global GPUs.
• OCR & Document Extraction: RapidOCR (ONNX runtime) combined with PyMuPDF (fitz) for spatial bounding-box layout clustering.
• Math Verification Service: Strict server-side Python calculations reconcile line-item arithmetic (Quantity × Rate = Amount, Subtotal + Tax = Grand Total) before auto-saving into SQLite.
• Tech Stack: React 19, TypeScript, Vite, Tailwind CSS v4, FastAPI, SQLAlchemy, SQLite, and ReportLab.

Why Does Open Innovation Matter?

1. Absolute Data Privacy: Invoices contain sensitive client information, bank details, and pricing margins. Closed APIs process and retain this data on their servers; running open-weight Qwen 2.5 on Ollama guarantees financial data never leaves the user's device.
2. Zero Marginal Cost: Closed AI APIs charge per token, making bulk invoice parsing cost-prohibitive. Open weights eliminate per-token charges entirely.
3. Offline Reliability: Small businesses and contractors often work in spots with spotty internet connectivity. BillCraft AI operates fully offline.
4. No Vendor Lock-In: Independent developers and businesses retain complete ownership over their infrastructure without fearing API price increases or unexpected deprecations.

My Agent Session

Throughout the development of BillCraft AI, I collaborated with Antigravity AI (Google DeepMind's agentic coding assistant) as an autonomous pair-programmer to:

• Architect the multi-stage OCR and Qwen 2.5 JSON parser with server-side validation.
• Build the full-stack UI using React 19 and Tailwind CSS v4.
• Streamline deployment to Render with static file integration and Cloudflare Workers AI edge fallback.

Prize Categories

• Open Source AI Champion
• Qwen 2.5 7B locally via Ollama
• Best Productivity / Developer Tool