Billwise — GST Billing & Quotation App

The challenge

An interior design business quotes on site and bills from the office. Every bill has to be a proper GST tax invoice (CGST and SGST within the state, IGST across states, HSN/SAC codes, the amount in words in lakh and crore), quotations turn into invoices, and part payments must be tracked against each one. Customers expect the bill on WhatsApp, and a phone at a site visit often has no signal.

Our solution

The web app works on a phone or a laptop and can be installed like an app. The server recomputes every total in whole paise and works out the tax split from the two states involved, and an invoice keeps a snapshot of the customer as billed, so later edits never change a past bill. Each business’s data is separated in every query. The Android app keeps its own database on the phone and syncs both ways when a connection returns; it reserves blocks of invoice numbers in advance, so a bill made offline already carries its final number. Sign-up is by invitation only, and a demo login with a sample business is open to anyone.

What we built

• Quotation to tax invoice to payment, with CGST/SGST or IGST worked out by the server
• Tax-invoice PDFs with an HSN/SAC tax summary and the amount in words, shared to WhatsApp
• Android app that bills offline and syncs later, with invoice numbers that never clash
• Bluetooth receipt printing, contacts import and a fingerprint or PIN lock on Android
• Each business’s data kept apart, checked by trying to open another business’s invoice