Devices

A device is a stable identifier for a physical phone, tablet, or computer in Rupt's data model. It sits one level above a fingerprint: multiple browsers on the same laptop produce different fingerprints but the same device. That's important for account sharing: an account with twelve fingerprints across two devices reads very differently from an account with twelve fingerprints across twelve devices.

How devices are identified

The mechanism depends on how the SDK is shipped:

• Native iOS: uses the Identifier for Vendor (IDFV). Stable across reinstalls of the same vendor's apps on the device, resets if every app from the vendor is uninstalled. Apple's anti-fingerprinting policy forbids more durable cross-app identifiers.
• Native Android: uses platform-provided device identifiers per Google's guidelines.
• Web: derived from the fingerprint plus persistent storage hints. Not as stable as a native device ID; treat web devices as best-effort.

What devices feed

Device counts are core to account-sharing detection:

• device_count: devices currently attached to the user.
• computer_device_count, tablet_device_count, mobile_device_count: broken out by type, since the thresholds for "too many" differ (one phone is fine, six laptops is suspicious).

These are exposed as checks so policies can match on them directly.

Devices vs fingerprints vs users

Rupt deliberately tracks all three layers:

• Fingerprint: narrowest. A specific browser instance.
• Device: broader. The physical hardware behind one or more fingerprints.
• User: your account-level identity, independent of hardware.

A single user may legitimately span multiple devices (laptop, phone, tablet). A single device may legitimately host multiple fingerprints (Chrome, Safari, work browser, personal browser). What's not legitimate is a single user with implausibly many devices. That's the sharing signal Rupt is built to catch, and the basis for the people estimate.