Promise of offline billing is cheap. The check is a live sale with the router off.
Do this on the computer the shop will actually use, with a garment that has a size and a colour, before you pay for a second device or a website.
Disconnect, then finish one bill
Turn off Wi-Fi. Restart the billing app. Scan the tag, or search for the product if the tag will not scan. Finish a cash sale. Print the receipt from that device. Confirm the stock for that size and colour went down, not the stock for a different size.
On VyaparNext POS Lite the bill and the stock change stay on the device. The receipt can still print. The customer’s UPI app still needs a network, so decide the cash fallback before the first Saturday outage. Staff can record Google Pay or PhonePe on the bill after the customer has paid.
Reconnect once
Turn Wi-Fi back on. If Cloud Sync is on, the bill should meet the other devices about every hour. Stock is rebuilt from sales and purchases. Look for a duplicate bill. If the same product was edited on two devices, the conflict is flagged and you pick what to keep.
A single counter without Cloud Sync does not need this step. The sale is already on that machine. Sync is what a second device needs. It is ₹299 a month on POS Lite, or included with Connected POS and Commerce.
What this test does not prove
A finished cash sale does not mean the software files GST. POS Lite prints a tax invoice with one tax rate: shop name, items, and total. It does not file a return.
It also does not prove the website shares that size. That starts when Commerce is on, at ₹35,000 setup and ₹1,800 a month.
Run the same drill on Cloud Sync details if you are comparing counters, and on the clothing POS page if the rack is garments. Free offline billing covers when one device is the whole shop.