Offline Transactions

Note

Offline Transactions is not enabled by default. Your organization must complete an opt-in process with the SumUp Integrations team and accept the related terms before using it.

Offline Transactions let merchants continue accepting card payments when internet connectivity is unavailable or unreliable. In this store-and-forward flow, card data is captured and cached securely on the device, then uploaded later for processing and authorization.

The feature is available for the Android SDK and iOS SDK. It is not available for Tap to Pay.

Caution

Offline transactions are provisionally approved on device without real-time authorization. The merchant bears the risk for transactions that are later declined during reconciliation.

Before You Begin

Make sure all of the following are true:

• You already have an active Android or iOS Reader SDK integration.
• The device and reader meet the minimum requirements below.
• The merchant has completed at least one successful online transaction.
• Your organization has completed the opt-in process for Offline Transactions.

To request access, contact us through the contact form.

Platform Availability

Capability	Android SDK	iOS SDK
Offline Transactions	Supported	Supported
Tap to Pay	❌ Not supported	❌ Not supported
Supported card schemes	Visa, Mastercard	Visa, Mastercard
Solo firmware	3.3.31.0 or higher	3.3.31.0 or higher
Solo Lite firmware	2.2.1.25 or higher	2.2.1.25 or higher

Geographic Availability

Offline Transactions are currently supported in Europe through Worldpay.

Minimum Requirements

Android

Requirement	Minimum
Android OS	Android 8
Card reader (Solo)	Firmware 3.3.31.0 or higher
Card reader (Solo Lite)	Firmware 2.2.1.25 or higher
Supported card schemes	Visa, Mastercard

iOS

Requirement	Minimum
iOS version	16.0 or higher
Secure Enclave	Required
Free storage	10 MB recommended
Card reader (Solo)	Firmware 3.3.31.0 or higher
Card reader (Solo Lite)	Firmware 2.2.1.25 or higher
Supported card schemes	Visa, Mastercard

Lifecycle

Offline Transactions follow four phases: preparation, activation, offline payment acceptance, and reconciliation.

Phase	What happens
Preparation	The SDK downloads offline rules and merchant limits while the device is online.
Activation	Your app starts an offline session.
Offline window	Transactions are validated locally, signed, and stored securely on device.
Reconciliation	Stored transactions are uploaded to SumUp when connectivity returns.

Preparation

Before going offline, sync the latest offline rules and limits while the device is online.

Android

• Method: SumUpAPI.updateOfflineSecurityPatch(SecurityPatchUpdateCallback callback)
• Internet required: Yes

If you skip this step, startOfflineSession(...) can fail with OfflineLimitsAbsent.

iOS

• Method: setupOfflineSession
• Internet required: Yes

Best practice: run preparation after merchant login or when the merchant explicitly enables offline mode.

Activation

Offline sessions are explicit on both platforms.

Android

• Start: SumUpAPI.startOfflineSession(StartOfflineSessionCallback callback)
• Internet required: No

iOS

• Start: startOfflineSession
• Internet required: No

Once an offline session starts, subsequent payments are attempted as offline transactions until the session is ended.

Note

The first offline transaction binds the session to the reader serial number. If the merchant switches readers mid-session, stop the session and start a new one with the new reader.

Offline Window

During an active offline session, transactions are validated locally and stored securely on the device. The SDK still returns an immediate result to your app.

Android

• Method: SumUpAPI.fetchCurrentOfflineSession(OfflineSessionCallback callback)
• Internet required: No
• Returns session information such as remaining time, approved transaction count, failed transaction count, and total approved amount.

iOS

• Methods: getOfflineSessionDetails, getOfflineSessionRemainingTime
• Internet required: No

Offline sessions are constrained by merchant limits, total stored volume, and session duration. Once those limits are reached or the session expires, new offline transactions are rejected.

Reconciliation

When connectivity returns, upload stored transactions as soon as possible.

Android

• Manual upload: SumUpAPI.uploadOfflineTransactions(UploadOfflineTransactionsStatusListener callback)
• End session: SumUpAPI.stopOfflineSession(StopOfflineSessionCallback callback)

Stopping the session also triggers an upload attempt.

iOS

• Manual upload: uploadOfflineSession
• End session: endOfflineSession

Android API Summary

API	Purpose	Internet required
SumUpAPI.updateOfflineSecurityPatch(...)	Download the latest offline rules and limits	Yes
SumUpAPI.startOfflineSession(...)	Start an offline session	No
SumUpAPI.stopOfflineSession(...)	Stop the session and trigger upload	No
SumUpAPI.uploadOfflineTransactions(...)	Upload stored offline transactions manually	Yes
SumUpAPI.fetchCurrentOfflineSession(...)	Inspect current session status	No

Android Integration Example

Update Offline Security Patch

SumUpAPI.updateOfflineSecurityPatch(new SecurityPatchUpdateCallback() {
    @Override
    public void onSuccess() {
        // Security patch update successful
    }

    @Override
    public void onFailure() {
        // Security patch update failed
    }
});

Start Offline Session

SumUpAPI.startOfflineSession(new StartOfflineSessionCallback() {
    @Override
    public void onResult(@NonNull StartOfflineSessionResult result) {
        // Handle the start result
    }
});

Stop Offline Session

SumUpAPI.stopOfflineSession(new StopOfflineSessionCallback() {
    @Override
    public void onResult(@NonNull StopOfflineSessionResult result) {
        // Handle the stop result
    }
});

Common Failure Modes

Scenario	Behavior
Preparation step skipped or failed	Session start can fail because offline limits are missing
Reader switched mid-session	Offline processing is suspended until a new session is started
Session expired	New offline transactions are rejected
Cumulative limit reached	New offline transactions are rejected until stored transactions are uploaded
Concurrent offline API calls	Not supported on Android; keep calls serial

Testing

For testing guidance, contact your SumUp technical contact or reach out through the contact form.