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To stop unexpected data transfers, map what your app and its embedded SDKs collect, where each field goes, and what triggers the transfer. Then remove data the feature does not need, configure or remove unnecessary SDKs, check each AI provider’s retention controls, and reconcile observed behavior with your platform disclosures. A store form or vendor privacy statement is not proof of what the app actually sends at runtime.

What counts as an unexpected data transfer?

An app’s data behavior includes code supplied by analytics, advertising, crash-reporting, fraud-prevention, and other SDK vendors—not just code your team wrote. A transfer may be an unintended privacy exposure even if it is not a security breach or deliberate misuse. Start by finding out what leaves the device and why; do not assume that a familiar SDK collects data only for the purpose named in its marketing.

This guide does not assess a particular app or establish how common a problem is across all apps. A 2024 preprint, “A Large-Scale Privacy Assessment of Android Third-Party SDKs”, examined 158 widely used Android SDKs and reported 338 instances of privacy-data exfiltration. The authors also reported that more than 30% of the examined SDKs lacked a privacy policy; among SDKs with privacy policies, 37% over-collected user data and 88% falsely claimed access to sensitive data. These are findings for that paper’s sample and methods, not estimates of all apps or SDKs.

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A 2025 preprint, “Fingerprinting SDKs for Mobile Apps and Where to Find Them”, attributed 30.56% of likely fingerprinting behaviors in its dataset to advertising SDKs and 23.92% to SDKs with an unknown or unclear purpose. Those percentages are likewise bounded by the study’s dataset and detection method; they should not be read as the share of all apps that fingerprint users.

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Map data, triggers, and destinations

Build an inventory before changing code. Follow each data type from its source, through the feature or event that uses it, to every recipient. Include first-party servers, AI APIs, analytics, crash reporting, advertising SDKs, app-controlled webviews, and server-to-server transfers. Record whether the information is optional or necessary, which identifiers travel with it, and whether transmission happens automatically or only after a user invokes a feature.

Record for each flow Questions to answer
Data and source What fields are collected or generated? Do they come from a form, device permission, user content, an identifier, or an app event?
Purpose and trigger Which feature needs the data? What screen, event, SDK initialization, or background process starts collection?
Identifiers and context Does the payload include an account ID, device or advertising identifier, location, timestamps, or context that could identify someone when combined?
Destination and recipient Which endpoint, provider, SDK vendor, or downstream service receives it? Does your own backend forward it elsewhere?
Necessity and control Can the feature work with fewer fields? Is collection optional? What consent, retention, deletion, or user setting applies?

Distinguish app-controlled webviews from users navigating the open web when assessing Google Play disclosures: Google’s guidance treats them differently. But data transmitted off-device by libraries and SDKs is in scope, and the developer is responsible for reviewing third-party code. See Google Play’s Data safety guidance.

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Audit the SDK supply chain

For each SDK in the project, document its purpose and version, vendor documentation, permissions, disclosure or manifest material, domains contacted, identifiers collected, initialization behavior, and whether it transmits data before the related feature is used. Compare that documentation with your inventory and observed app behavior; an SDK’s name or stated purpose is not enough to establish what it does.

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  • Ask the vendor what data the SDK receives, how long it retains it, whether it acts only on your instructions, and whether it uses data to build profiles across customers.
  • Check whether collection is automatic at startup or conditional on a particular feature, consent state, or configuration.
  • Remove an SDK if its collection is unnecessary or its behavior cannot be reconciled with the feature and disclosures.
  • Review updates and changes to SDK behavior as part of release maintenance, not only at initial integration.

Google warns that an SDK described as anti-fraud can still violate policy if it also sends data to third parties for advertising or analytics. Its SDK requirements also make clear that third-party code must not cause a policy violation. Apple says developers remain responsible for all code included in their apps and recommends contacting the SDK developer when practices are unclear; see Apple’s privacy and data-use guidance.

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Reduce what AI APIs receive—and check retention separately

Before a feature sends content to an AI provider, identify the provider and endpoint, the information in the request, any relevant data region, the applicable storage setting, and the available deletion mechanism. Send the smallest payload that can do the job: remove direct identifiers and unrelated context where feasible, and avoid transmitting secrets or a complete record when a short excerpt is sufficient.

Do not treat model training, abuse monitoring, and application-state storage as interchangeable. For the OpenAI API specifically, its documentation says API data is not used to train or improve models by default. The same documentation says abuse-monitoring logs can contain prompts, responses, and derived metadata and are retained for up to 30 days by default, subject to exceptions. Endpoint behavior and application-state retention vary, and some retention controls require approval. Check the current settings and terms for the exact API and features you use in OpenAI’s API data controls documentation; these details are provider-specific, not a rule for every AI service.

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Choose controls that address different risks

No single measure solves every data-flow problem. Use source minimization to reduce exposure, provider settings to govern transfers you still need, SDK controls to limit third-party collection, consent mechanisms where required, and disclosure reconciliation to keep representations accurate.

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Approach What it changes What it does not replace
Data minimization Reduces collection or the fields sent at source; some information may remain on-device. It does not configure retention for data the feature still sends or establish that runtime behavior matches disclosures.
AI provider retention controls Govern storage or retention for a transfer the app continues to make, subject to the provider, endpoint, and available settings. They do not make an unnecessary payload necessary or automatically cover another vendor.
SDK removal or configuration Removes an unnecessary recipient or changes when and how its code collects data. It does not by itself update platform disclosures or address other SDKs and first-party flows.
Platform consent Enables or blocks covered collection or tracking according to platform rules and the user’s choice. Consent is not a substitute for minimizing data or disclosing the app’s actual behavior.
Disclosure reconciliation Aligns store declarations and privacy notices with the app’s code, SDKs, and observed transfers. A declaration describes data use; it does not independently prevent or verify a transfer.

OWASP Mobile Application Security’s MASVS-PRIVACY-1 states: “Apps should only request access to the data they absolutely need for their functionality and always with informed consent from the user.” Apply that principle before relying on downstream settings to manage data already collected.

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Apply the platform rules to actual behavior

Apple platforms: assess tracking and privacy disclosures

Apple’s App Tracking Transparency (ATT) applies to covered tracking that links app or device data with data from other companies’ apps, websites, or offline properties for targeted advertising or measurement, as well as sharing with data brokers. Apple gives the example of a third-party SDK combining information collected by your app with data from other developers’ apps, even if you say you did not use that SDK for this purpose. A hashed identifier is not a workaround: Apple says another identifier cannot be used to track a user without the required permission. Review Apple’s guidance on privacy and data use for the scope and applicable requirements.

Apple Privacy Manifests describe data collected and used by third-party code such as advertising or analytics SDKs. Xcode can combine manifests into a report to support accurate App Store privacy details. Treat those materials as inputs to an audit, not as confirmation that runtime behavior matches them; developers remain responsible for the code in the app.

Google Play: include SDK collection in Data safety

Google Play’s Data safety form must reflect collection and sharing by libraries and SDKs, not just the app’s own code. Google says pseudonymous data should still be disclosed if it can reasonably be re-associated with a user. It also says SDK activity that builds advertising profiles across multiple customers is not treated as service-provider processing for the form. Consult Google’s Data safety guidance and compare the answers with the complete flow inventory.

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Turn the audit into a release process

  1. Inventory: List the app’s data types, triggers, identifiers, SDKs, APIs, and downstream recipients. Include background activity and server-to-server forwarding.
  2. Verify: Compare the code and SDK configuration with vendor documentation and observed destinations. Investigate transfers that are undocumented, unexpected, or triggered before the related feature is used.
  3. Reduce: Delete unnecessary SDKs and permissions, remove unneeded fields and identifiers from payloads, and keep data on-device where a feature can work without sending it away.
  4. Gate: Where appropriate, initialize an SDK only when its feature is needed. Configure consent before enabling collection covered by platform requirements, and apply provider retention settings to transfers that remain.
  5. Protect: Use secure transport for sensitive information and check whether SDKs have known vulnerabilities. Google Play also requires secure handling of personal and sensitive data.
  6. Reconcile: Compare observed behavior and configuration with Apple privacy manifests and App Store privacy details, Google Play Data safety declarations, and your privacy notices. Correct either the implementation or the disclosure when they do not match.
  7. Repeat: Revisit the inventory when adding or updating an SDK, AI endpoint, feature, or permission, and before a release changes data collection or sharing.

A store declaration is not runtime verification. Google’s guidance places responsibility on developers to review third-party code, while Apple says developers are responsible for code included in their apps. For teams seeking an external check, Google describes an optional paid independent security review through its Mobile Application Security Assessment (MASA) program, evaluated against OWASP MASVS; it is not a universal requirement. Current policies and provider controls can change, so confirm the applicable documentation and settings when implementing changes.

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