Fireworks POS — offline point of sale for a retail shop
Offline LAN point-of-sale for a fireworks shop: cash checkout with 80mm receipts, lot-traceable inventory, returns with an audit trail, sales analytics.
Sole engineer · 2026
Problem
A fireworks shop sells hardest exactly when connectivity is worst — seasonal rush, cash-only counters, and a product category where regulators expect you to trace what was sold back to a supplier lot. Cloud POS subscriptions assume an internet connection the shop does not have.
What I built
A self-hosted point of sale that runs as a server on one shop PC; cashier and admin devices on the same LAN use it from a browser. No internet is required at any point of a sale.
Cash checkout with change math and 80mm thermal or PDF receipts. Inventory with stock-in by batch/lot and supplier, low-stock alerts, cost and margin tracking, and lot-to-sales recall — pick a lot and see every sale it went into. Returns, refunds, and voids restore stock and land in an audit trail. Two roles (superadmin, cashier) with server-side authorization. One-click and nightly backups of the single-file SQLite database, plus CSV exports. For shop staff, starting it means double-clicking a launcher that prints the LAN address to open on any device.
Result
A working shop system that needs nothing but one PC and a LAN: sales, inventory, traceability, and analytics (revenue over time, top and slow sellers, per-cashier totals, profit and margin) — converged at 100% of its acceptance suite, end-to-end browser tests included.
