Munim: a bill diary that tells kirana owners when a supplier quietly raised the price

Description and use

Munim is a local-first bill diary for small Indian shops that captures supplier bills, validates data, alerts on price changes, tracks dues, and exports month‑end packs, all powered by the open‑weight Gemma 3 vision model running locally.

Problem

Shop owners struggle with paper bills, manual entry, and unnoticed price changes from suppliers.

Outcome

On a synthetic dataset of 30 bills, Munim surfaced all six planted price changes and savings, reduced review queue from 29 to 3 flagged bills after fixing validation logic, and demonstrated zero per‑bill API cost.

Workflow

• Photograph supplier bill with phone
• Upload photo via local QR‑code page
• Gemma 3 vision model parses bill into JSON
• Go backend validates GSTIN, totals, and tax
• Normalize items and match with last bill and 3‑bill median
• Generate price‑change alerts if evidence exists
• Update supplier dues table with new bill
• Export month‑end CSV/Tally pack for CA
• Review any bills flagged by validation errors

Evidence

Munim reads them using Google's open-weight Gemma 3 vision model served locally via Ollama

Source

Zero per-bill API cost.

Source

The design rule I followed: the model reads, the code decides.

Source

On the synthetic dataset (30 bills across three fictional distributors over roughly two months), I planted five price hikes and one case where another supplier sells the same item cheaper. Munim surfaced all six, one alert each, with both invoices as evidence.

Source