A browser-based or mobile-app-based identifier for a unique, pseudonymous website or mobile app user.
On a website, device ID gets its value from the client ID property of the _ga cookie. In an iOS or Firebase app, device ID gets its value from the app-instance ID, which identifies a unique installation of the app. Currently, there is no character limit for the client ID and the resulting device ID.
Device ID is one of the available reporting identity spaces.
Related resources
- Data collection (opens in the Firebase Help Center)
- Automatically generated and assigned app-instance ID
- Google tag API reference