Billing without internet: how offline billing works, and what to watch for

The short answer

Offline billing saves each bill on the billing device when the internet drops, gives the customer a provisional bill, and sends the saved bills to the server when the connection returns. Done well, each bill is sent exactly once, in the order it was made, and any bill the server can't accept waits for you instead of disappearing.

Why the internet matters at the counter

A cloud billing app normally checks stock, works out tax and offers, and gives the bill its number on the server. When the shop's Wi-Fi or mobile data drops, that check can't happen, and a queue forms at the counter.

Offline billing lets simple sales carry on, and does the server's part later.

What happens to an offline bill, step by step

1. 1.The app keeps a copy of your item list on the device, so search and barcode scanning still work.
2. 2.You press Pay. With no connection, the bill is saved on the device with a temporary number.
3. 3.The customer gets a provisional bill, printed or shown, marked as provisional.
4. 4.When the internet is back, saved bills are sent one at a time, oldest first.
5. 5.Each bill gets its final number, and the stock is taken.
6. 6.A bill the server refuses, for example because the item sold out online meanwhile, is kept for you to review.

The two risks: double bills and overselling

Double bills happen when an app sends a bill, loses the reply on a weak connection, and sends it again. The fix is a unique key on every bill, so the server accepts each key once, however many times it arrives.

Overselling happens when the counter sells a piece offline that the website sold online. No app can prevent this while it is offline. What matters is that the clash is caught when the bill syncs and shown to you, so you can sort it out with the customer.

Tips for billing through a bad connection

• Switch offline billing on before you need it, and open the billing screen once on each device while you are online.
• Use a normal browser window. Private windows usually can't keep data on the device.
• Take cash or UPI while offline, and check the UPI payment on your own phone before you hand over the goods.
• Keep a mobile hotspot as a backup so saved bills can sync during the day.
• Look at bills that need attention before you close the day.

How offline billing works on Slaby

In Slaby, offline billing is a counter setting, Keep billing when the internet drops, and it is off until you switch it on. Offline bills are cash or UPI only; card, udhaar, coupons, points and store credit wait for the internet. Totals on an offline bill are an estimate, and tax and offers are worked out when it syncs.

Saved bills sync in order with a unique key each, so a bill is never billed twice. Only one browser tab on a device syncs at a time. A bill that can't go through moves to Needs attention, where you retry it, edit and resend it, or close it with a note. Nothing is deleted without you.

Offline billing is part of counter billing, which comes with every paid plan, from Lite at ₹299 a month, after a 14-day free trial.

Common questions

Can I take card payments offline?

On Slaby, no. Offline bills are cash or UPI. Card, udhaar, coupons, points and store credit need the internet.

What number does an offline bill get?

A provisional number on the device. It gets its final bill number from your normal series when it syncs.

What if the device is switched off before the bills sync?

Saved bills stay on the device and sync the next time billing is open with an internet connection, as long as the browser's site data isn't cleared.

Does offline billing work on a phone?

Yes, in a normal browser window on the phone, tablet or PC you bill on.

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