Offline Transactions

Use store-and-forward offline transactions with the Android and iOS Reader SDKs, including requirements, lifecycle, and platform-specific APIs.

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.

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 integrations@sumup.com.

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.

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

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
iOS

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

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

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
iOS

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

Start: startOfflineSession
Internet required: No

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

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
iOS

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.

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
iOS

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

Stopping the session also triggers an upload attempt.

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

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

Start Offline Session

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

Stop Offline Session

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

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 integrations@sumup.com.