Android vs iOS pentesting.

Shared. The backend API is the same for both platforms. The authorisation logic, the data model, and the server-side business rules are tested once and apply to both apps. In practice this is where most high-impact findings live, regardless of platform.

Different. Almost everything on the device:

• The programming languages (Kotlin / Java on Android, Swift / Objective-C on iOS).
• The package format (APK or AAB on Android, IPA on iOS).
• How easy the binary is to decompile and read.
• The platform's openness and how the tester gains the device access needed to test.
• The on-device storage mechanisms and their default protections.
• The common implementation mistakes each platform's developers make.

Android is the more open platform, which makes testing more straightforward.

• Decompilation is easy. Android apps compile to a bytecode that decompiles back to near-readable Java or Kotlin. Hardcoded secrets, logic, and API endpoints are usually quick to recover.
• Rooting is accessible. Test devices and emulators can be rooted readily, giving the tester full control.
• The component model is an attack surface. Android apps expose components (activities, services, broadcast receivers, content providers) that other apps can interact with. Exported components that should be private are a common finding.
• Inter-process communication via Intents. Deep links and Intents are a common path for an attacker app or a crafted link to reach functionality it should not.
• Storage defaults. Shared preferences and local databases are unencrypted by default. Sensitive data stored there is a frequent finding.

iOS is the more locked-down platform, which makes testing require more setup but does not make apps secure by default.

• Decompilation is harder but not impossible. iOS binaries are compiled to native machine code, which is harder to read than Android bytecode, but the strings, embedded secrets, and structure are still recoverable.
• Jailbreaking is required for deep testing. A jailbroken device or a specialised testing setup is needed to instrument the app and inspect the file system.
• The Keychain is the right place for secrets. iOS provides the Keychain for secure storage. A common finding is sensitive data stored outside the Keychain, in plist files, in the app's documents directory, or in caches.
• URL schemes and universal links. The iOS equivalent of Android's deep-link attack surface. Crafted links can reach app functionality.
• Pasteboard and backgrounding leaks. iOS-specific data-exposure findings, like sensitive data left on the shared pasteboard or captured in the app-switcher snapshot.

Some tools are cross-platform, some are platform-specific.

• Cross-platform. The open-source instrumentation toolkit Frida works on both, and is the backbone of runtime testing for either platform. Network interception tooling is also shared.
• Android-specific. Decompilers and bytecode tools, the Android Debug Bridge, and emulator-based testing.
• iOS-specific. Jailbreak tooling, the iOS file-system access tools, and binary-analysis tools tuned for native code.

The technique is the same on both platforms (static analysis, dynamic analysis, network and API testing); the specific tools and the effort to set up the test environment differ.

Test the platform with the larger user base or the more sensitive use case first, but understand the limit: testing one platform only covers that platform's client. The backend API is shared and gets tested either way, which is the most important part. The platform-specific client findings (storage, deep links, protections) only apply to the platform you tested.

For most teams the right answer is to test both clients (because the platform-specific findings differ) while testing the shared API once. The incremental cost of the second platform is lower than the first because the API work is already done.