Definition:
IDFV (Identifier for Vendors) is a unique identifier assigned by Apple to an app on a specific iOS device. It is used to identify and distinguish one app from others on the same device, and to help developers track app usage and manage their data without relying on user-level advertising identifiers.
What is IDFV?
The IDFV is an Apple-assigned identifier that links an app to a specific device. It is unique to the combination of app and device, meaning the same app installed on two different devices will produce two different IDFVs. It is also vendor-specific, so two different apps from the same developer installed on the same device will each have their own IDFV.
Unlike the IDFA, the IDFV does not require user permission to access. It is available to the app developer by default and is intended for first-party use — tracking and managing the developer's own data on a device, rather than enabling cross-app advertising or third-party tracking.
A developer might use the IDFV to understand how frequently their app is used on a particular device, or to recognize a device that has interacted with their app before — without needing access to any advertising identifier.
IDFV vs IDFA: What is the Difference?
Both are iOS identifiers, but they serve different purposes and operate under very different rules.
| Identifier | Assigned To | Primary Use | Requires User Permission |
| IDFA | The device | Advertising and cross-app tracking | Yes, via ATT prompt |
| IDFV | The app on a specific device | First-party app usage tracking | No |
The IDFA is a device-level identifier used by advertisers to track users across apps and websites for targeting and attribution purposes. Since iOS 14.5 and the introduction of App Tracking Transparency, accessing the IDFA requires explicit user opt-in. When a user declines, the IDFA is replaced with a string of zeros, making individual-level ad tracking impossible for that user.
The IDFV operates differently. It is scoped to the vendor, the developer or puclihser, rather than to advertisers broadly. It does not require an ATT prompt and remains accessible regardless of a user's ATT choice. This makes it a more reliable and consistent identifier in a post-ATT environment.
Why IDFV Has Become More Important
Before iOS 14.5, IDFA was the primary identifier used for mobile attribution and user tracking on iOS. When ATT significantly reduced IDFA availability, the industry needed alternatives.
Tenjin defaults to IDFV for this reason. If a user opts out of tracking or opts in at a later stage Tenjin registers the user with their IDFV to maintain consistency and avoid gaps or inaccuracies in the data. This means attribution and engagement data remains as complete and reliable as possible, even when IDFA is unavailable.
It is not a perfect replacement for IDFA in every context since IDFV cannot be used for cross-app tracking or third-party advertising in the way IDFA can. But for first-party measurement and attribution within a developer's own ecosystem, it is a stable and privacy-compliant foundation.
What Is the Android Equivalent of IDFV?
On Android, the closest equivalent to IDFV is the Android ID. Like IDFV, the Android ID is a unique identifier tied to a specific device. It is generated when the device is first set up and remains consistent for the lifetime of the device, unless the device is factory reset.
The Android ID is used to identify a device and distinguish it from others, serving a similar first-party identification role to the IDFV on iOS. It is worth noting that Android's approach to privacy and identifier management continues to evolve, with Google making ongoing changes to how advertising identifiers like the GAID can be accessed and used.
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