How do restaurants keep taking orders during an outage?

A cloud point-of-sale system depends on two things working: the restaurant’s own internet connection and the vendor’s servers. Square’s offline payments guide treats these separately, as an internet outage or a Square service disruption, and so does Toast. Toast says its devices switch to Offline Mode automatically when they lose the internet, the local network, or the Toast cloud, and show a banner after about 40 seconds without a connection.

The distinction matters for what to do next. A local outage is something the restaurant can troubleshoot itself, at the router or with its internet provider. A vendor outage needs patience, and Toast tells restaurants not to unplug, restart or reset equipment while one is in progress.

Normally the till learns whether a card is approved while the guest waits. Offline, the till takes the card details, stores the payment on the device and submits it later, a store-and-forward arrangement with a time limit.

Square spells out the terms:

• Offline payments are stored in the point-of-sale app and process automatically once the device reconnects.
• They must be uploaded within 72 hours of the start of the offline session, and Square highly recommends doing it within 24 hours to reduce the risk of chargebacks and declines. Pending payments not uploaded in time expire and cannot be recovered.
• Declines are not shown at the till. The seller sees declined or failed payments only after reconnecting, and is responsible for any that are expired, declined or disputed.
• Some methods do not work offline, including Tap to Pay on iPhone and Android, Square gift cards and manually entered card numbers.
• Sellers can set a maximum amount per offline transaction, anywhere from $1 to $50,000.

Toast works the same way in outline. Card payments and tips continue as long as background card processing is enabled, which is the default. Guest receipts show an authorisation status of Pending rather than Approved, and pre-authorisation only works if the card was pre-authorised before the outage began. Toast also tells restaurants they are responsible for declined, expired or disputed offline transactions.

Taking an order is only half the job. The kitchen has to see it. Receipt printers and cash drawers keep working on Toast as long as the Ethernet cables stay connected. For kitchen display screens, Toast’s Offline Mode can keep sending tickets for new in-store orders, but only if the network meets two conditions: Universal Plug and Play multicast traffic is enabled on the router, and at least one hardwired Toast device is on the network to act as the local hub. Toast adds that the hub only talks to devices on its own subnet.

That is a small piece of local, device-to-device coordination, and it shows what is normally missing. Toast’s guidance for staff during an outage is to stick to one device per employee, so that order and payment information stays together. That advice implies open checks are not reliably shared between devices until the system is back online. Menu edits, including marking items as sold out, are unavailable offline.

Orders from outside the building cannot reach a restaurant that is not connected. Toast says its online ordering page stops accepting new orders once the system detects that they are not getting through, which can take up to five minutes, and suggests pausing Mobile Order and Pay so guests cannot pay for orders the kitchen will not see. Square notes that new online orders, including those from ordering platforms such as Uber Eats, may not appear in the POS until the disruption is resolved.

Orders accepted just before the cut-off still arrive when the connection returns. With auto-fire enabled on Toast, they fire to the kitchen straight away, and Toast suggests contacting guests to check they still want an order before preparing it.

Coming back online is a reconciliation job:

• Stored card payments upload and settle, and declines appear for the first time.
• Reports leave out offline devices until they sync.
• On Toast, closing checks, reconciling cash and tips, and clocking out wait until devices reconnect, and Toast advises against running payroll while devices are offline.
• Loyalty points earned offline have to be linked by hand on Square.

Toast warns about one risk in particular. Logging out while offline means nobody can log back in until the connection returns, and uninstalling the app loses the order and payment data held on that device. Until it uploads, the device is the only copy.

The pattern above is a set of devices that each keep working alone, and a cloud that stitches their records together afterwards. The gaps sit between the devices: a check that only one till can see, an item sold out at the counter but still offered at the drive-thru, a kitchen that cannot confirm it has a ticket.

Sharing that state directly between the devices in the restaurant closes some of those gaps. For it to be safe, each order needs a stable ID so a resent order is applied once (see idempotency), and the sending device needs to know the difference between an order that was delivered and one the kitchen accepted. Local sync does not change the payment side. A card payment taken offline still has to reach the card network before anyone knows whether it was approved.