Make a bill. Then take the network away.
Tap three things off the shelf, take the payment, and look at the receipt. Then cut the network and do it again — the second bill saves exactly like the first, which is the one claim this product is actually built around and the one worth checking rather than believing.
The switch is the one dishonest thing on this page: at a real counter there is no switch. The app behaves this way because the signal went, not because anyone chose it — you are being given a button for something that normally happens to you.
Tap items off the shelf below or tap Scan. Three items is enough to see how this goes.
The receipt, as you build it
No GSTIN on it, because this shop has not set one — put one in and it prints, along with the bill's tax total, and it stops there. No watermark, and no line saying which app made it. The receipt is the shop's signboard, not ours, and that is written down rather than currently true.
This is a drawing, running in your browser. Nothing is saved, nothing is sent anywhere, and there is no account behind it — reload the page and it is gone. The real thing runs on the phone already at your counter, and the difference that matters is the one you cannot see here: on the phone the bill is written to storage before anything else happens, which is why the network switch above makes no difference to whether it saves.
The bill was never sent anywhere to be made
In most billing software a sale is a request: the total, the stock decrement and the receipt number are decided by a server, so with the tower down the screen becomes a spinner or a refusal. Here the bill is written down first and sent afterwards, which is why the switch above changes what the screen says and not whether the sale happens.