What goes wrong when the signal drops
- The app opens but will not save the bill, so the customer waits or the sale is written on paper and forgotten later.
- The app shows the bill but cannot print or share it.
- Worst: the payment is retried when the signal returns, and the customer is billed twice.
What “works offline” should mean
A billing app is truly offline only if all of these happen on the phone, with no internet:
- Searching or scanning the products you sell.
- Building the cart, with weights and quantities.
- Taking the payment: cash, UPI received, card or credit.
- Saving the bill and giving the receipt.
- Taking the items out of stock.
Then, when the signal returns, the saved bills should upload by themselves, and a payment that was retried should return the same bill, never a second one.
A five-minute test for any billing app
- Turn on aeroplane mode.
- Make a bill with three items, one of them weighed. Take a payment.
- Share or print the receipt.
- Make two more bills. Close the app and open it again: are all three still there?
- Turn aeroplane mode off and wait a minute. Do all three bills appear online, once each?
If any step fails, that app will fail you on a busy evening.
A word about UPI when the network is down
A UPI payment needs the customer’s phone to have a connection, and the confirmation needs yours. If a payment shows as pending, do not mark the bill paid until you see the money arrive. Take cash, or put the amount on the customer’s khata until it clears.
How DukanUp handles it
In DukanUp, search, the cart, payment, the receipt and the stock update all run on the phone. Bills are saved on the phone and upload themselves when the connection returns. Every bill gets its own id when the cart opens, so if a payment is retried after a dropped connection, the server returns the original bill instead of creating a second one.
Honest limits: voice billing needs a connection on most phones, because the phone’s speech recogniser does. Adding a brand-new product from the ready product list, running reports and changing settings need a connection too. Billing the products you already sell never does.
Questions
Can I bill with no internet at all in DukanUp?
Yes. Search, cart, payment, the receipt and the stock update all run on the phone, and the bill uploads itself when the connection returns.
What happens if the network drops while I am taking payment?
Every bill gets an id when the cart opens. If the phone sends it again because it never heard back, the server returns the original bill rather than making a second one, so the customer is never charged twice.
Does barcode scanning work offline?
Scanning the products you have already added works offline. Looking up a packet you have never sold in the ready product list needs a connection.
