What keeps working
Raising a bill, recording a cash or credit sale, taking a payment and printing a receipt, logging a delivery, and looking up a party's balance all work with no connection. The data sits on the phone and uploads the moment coverage returns — there is no queue to manage and no sync button to remember. Thermal printing over Bluetooth works throughout, so the customer notices nothing.
What genuinely needs a connection
Anything that has to reach the server live: sending a WhatsApp message, and seeing something a staff member recorded on another device in the last few minutes. Being straight about that matters more than claiming everything works — you should know which two things will wait, so they are not a surprise during an outage.
Where this is used most
Shops in small towns and hill districts with patchy coverage, godowns with thick walls and no signal, trucks delivering to sites hours from anywhere, and every shop in a state with regular power cuts. It is also what keeps the counter moving during the outage that happens two or three times a week across much of the country. The point is not that you plan to work offline — it is that when it happens, nobody stands waiting.
Why not fully offline desktop software
Installed software works in a power cut and also keeps your entire trading history on one machine at the counter, exposed to theft, a failed disk and ransomware, backed up only when somebody remembers. You also cannot bill from a site and a second branch needs a second installation. Offline capability is worth having; paying for it with a single point of failure is not.
What to check after an outage
Two things, and only two. Open the app once you have signal and confirm the sync has completed — it happens on its own but a glance costs nothing. Then check that anything a second person recorded on another device during the outage has come through, because that is the one thing that could not reach you while you were offline. Shops that make this a habit after a long cut never discover a missing day a fortnight later, which is the only failure mode worth guarding against.