# Can a POS work without internet? Offline POS explained

> Yes, a POS can work without internet if it is built to sell offline. It keeps the products, prices and staff it needs on the till itself, saves each sale there, and sends the sales to the server in order when the connection returns. Things that depend on the server, such as M-Pesa prompts and up-to-date reports, wait until the till is back online.

## In short

- A POS built for offline use keeps selling, taking payment and printing receipts when the internet drops.
- Offline sales are saved on the till and sent, in order, when the connection returns.
- M-Pesa prompts, other tills’ sales and current reports need a connection; recording an M-Pesa code does not.
- Never clear browser data on a till with unsent sales, and check that it has synced before closing a shift.

## Can a POS system work without internet?

Yes, if it was built for it. An offline POS keeps a copy of everything it needs to sell on the till itself, so scanning, totalling, taking payment and printing receipts carry on when the internet drops. Sales made offline are sent to the server once the connection is back.

Not every cloud POS works this way. Some show an error the moment the connection drops, and the queue waits until it returns. In Kenya, where a blackout can take the router down and a data bundle can run out in the middle of the afternoon, that difference decides whether you keep trading.

## How does an offline POS work?

An offline POS works "local-first": the till does the selling, and the server keeps the shared record. The till needs the internet to exchange news with the server, not to make a sale.

In plain words, it goes like this:

1. **While online,** the till downloads the products, prices, customers and staff it needs, and keeps them on the device.
2. **At each sale,** the till looks up prices in its own copy, records the sale and the payment on the device and prints the receipt. It does not wait for the server.
3. **Each sale joins a queue** of work waiting to be sent, in the order it was made.
4. **When there is a connection,** the till sends the queue to the server one sale at a time, and collects any changes, such as new prices.
5. **The server checks each sale** and adds it to stock, reports and customer accounts.

A well-built system gives every sale its own unique identity, so a sale that is sent twice, because the connection dropped halfway, is still recorded only once.

## What works offline, and what needs a connection?

Selling works offline; anything that needs other tills, other branches or an outside service needs a connection. The exact list depends on the system, so check it, but this is typical:

| Usually works offline | Needs a connection |
| --- | --- |
| Scanning and searching for products | M-Pesa prompts (STK push) |
| Totals, discounts and VAT | Seeing sales from other tills and branches |
| Cash payments, and M-Pesa or card payments you record | Up-to-date reports and the dashboard |
| Printing receipts on a connected printer | New products and price changes reaching the till |
| Saving each sale on the till | Back-office work such as receiving stock and changing settings |

M-Pesa itself does not depend on your shop's internet. A customer can still pay your till number over the mobile network while your router is down; the cashier records the transaction code at the till, and you confirm the payment on the shop's M-Pesa messages as usual. [Accepting M-Pesa payments](https://wavepos.app/guides/accept-mpesa-payments) covers that in detail.

## What happens to receipt numbers when a till is offline?

A good offline POS keeps receipt numbers in order with no gaps, even when several tills are offline at once. One common way is to give each till its own numbering series, so two tills can never hand out the same number.

Gaps and duplicates both cause trouble. A missing receipt number looks like a deleted sale, and two receipts with the same number confuse returns and audits. Ask any vendor exactly how numbering works when a till is offline.

## What happens if a price changes while a till is offline?

The till keeps selling at the price it last knew, because it cannot hear about the change until it reconnects. A good system then accepts those sales as they were made, since that is what the customer paid, and flags them for a manager to review.

Here is an example. At 11:00, a manager at head office raises 1 litre of cooking oil from KSh 380 to KSh 400 for the Kisumu branch. One Kisumu till has been offline since 10:30, and it sells six more bottles at KSh 380 before it reconnects at 13:00. When those sales arrive they are recorded at KSh 380, KSh 2,280 in all and KSh 120 less than at the new price, and flagged so the manager can see why.

The same applies to other things that change while a till is away: a cashier whose access was removed, or the last item on the shelf sold by two tills at once. These are matters to review, not reasons to throw away a sale the customer has already paid for.

## How do offline sales sync when the internet is back?

When the connection returns, the till sends its waiting sales to the server in the order they were made, without anyone pressing a button. Each sale then lands in stock, reports and customer accounts, with the time it was actually made.

Now and then a sale cannot be accepted as it stands, for example because something it refers to was changed or removed in the meantime. A good system does not throw such a sale away: it keeps it aside for a manager to look at and decide.

## How does Wave POS handle offline selling?

Wave POS keeps selling offline. Sales are saved on the till and sent, in order, when the internet is back, and receipt numbers have no gaps, even offline.

- If something changed while a till was offline, a price for example, the sale is still accepted and flagged for a manager.
- Anything a till could not send waits under "Sync issues" for review, rather than being lost.
- Each till is registered, and you can see when it last synced, so a till that has been offline for days stands out.
- M-Pesa prompts need a connection; while offline, the cashier records the M-Pesa payment and its code instead.

Wave POS runs in Chrome and can be installed as an app from Chrome, so the till's waiting sales are kept in the browser on that device. That is why the habits below matter. [Offline selling](https://wavepos.app/features/offline-pos) has more on how it works at the till.

## What are the risks of selling offline, and how do you avoid them?

The main risk is that unsent sales exist only on the till until they are sent. If the device is wiped, lost or broken before then, those sales go with it. A few habits keep them safe:

- **Do not clear browser data on a till with unsent sales.** Clearing cookies and site data, or "clearing history" with everything ticked, can delete the sales waiting to be sent. Make sure the till has synced first.
- **Do not use a private or incognito window as a till.** Everything in it is thrown away when the window closes.
- **Check sync before closing a shift.** Before the cashier counts the drawer and signs off, make sure the till shows that everything has been sent. [Cash drawer reconciliation](https://wavepos.app/guides/cash-drawer-reconciliation) covers the count itself.
- **Keep the till powered during blackouts.** A laptop with a charged battery, or a desktop and router on a UPS, keeps selling and keeps the router up so sales can be sent.
- **Have a backup connection.** A phone hotspot with a data bundle is enough to send waiting sales when the shop's internet is down for long.
- **Bring every till online at least once a day.** The longer a till stays offline, the older its prices are and the longer its sales are missing from your reports.
- **Sync before you change devices.** Do not reset, replace or hand over a till's computer or tablet until it has sent everything.

### A worked example

A shop in Nakuru loses its internet at 10:00 on a Saturday, and it comes back at 13:30. In between, the two tills make 48 sales worth KSh 61,400, with some paid in cash and some by M-Pesa codes the cashiers record. Nothing stops at the counter. When the connection returns, both tills send their sales in order, the dashboard catches up, and the owner checks that each till shows a recent sync before the afternoon shift closes.

## What should you ask a vendor about offline mode?

Ask these questions before you buy any POS, then test the answers during a trial by switching off the Wi-Fi:

1. Can I make a sale, take payment and print a receipt with no internet at all?
2. Can the till start up with no internet, for example after a restart during a blackout?
3. How are receipt numbers kept unique, and free of gaps, while tills are offline?
4. What happens to a sale made at an old price?
5. Where do sales that fail to sync go, and who gets to see them?
6. Can I see when each till last synced?
7. Which features stop working offline?
8. What happens to unsent sales if someone clears the browser data?

For the rest of what to compare between systems, see [how to choose a POS system](https://wavepos.app/guides/how-to-choose-a-pos-system).

## Frequently asked questions

### Can a POS work without internet?

Yes, if it is built for offline selling. It keeps products and prices on the till, saves each sale there and sends it to the server when the connection returns. Wave POS works this way, with receipt numbers that have no gaps even offline. Sending M-Pesa prompts needs a connection.

### What happens to sales made offline?

They wait on the till and are sent to the server, in order, when the connection is back. In Wave POS, a sale affected by a change made while the till was offline, such as a new price, is still accepted and flagged for a manager, and anything that could not be sent waits under Sync issues for review.

### Can I accept M-Pesa when the internet is down?

Yes. Customers pay your till number over the mobile network, which does not depend on your shop’s internet. Record the transaction code at the till and confirm the payment on your own M-Pesa records. Sending an M-Pesa prompt from the till does need a connection.

### How long can a till stay offline?

It depends on the system, but the shorter the better. A till that stays offline for days sells at old prices, and its sales are missing from stock and reports until it syncs. Bring every till online at least once a day, and check when each one last synced.

### Will I lose sales if the power goes off?

No, not if your POS saves each sale on the till as it is made. The sale stays on the device through the power cut and is sent once the till is back on and online. A UPS or a charged laptop battery lets you keep selling through the blackout.

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Source: https://wavepos.app/guides/offline-pos-explained
Last updated: 2026-10-11