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Apple heavily advertises privacy for its products, like the iPhone. These are usually one of the big talking points in their announcements, which makes your iPhone feel pretty locked down. This is true until you see how much ordinary device data apps can quietly read.
Security research team Mysk has launched Loupe: What Apps Can See, a free iOS app designed to show users what information third-party apps can access through public iOS APIs. The app is available on the App Store for iPhone and iPad, listed under Developer Tools, and requires iOS 17 or later.
Why Loupe is not a spy detector
Loupe is not built to inform you what Instagram, TikTok, Facebook, or any specific app is doing in real time. Rather, it shows the kinds of devicesignals that apps can read from your iPhone using the same public APIs available to developers. Loupe even gives users a “hands-on tour” of the device fingerprinting surface. The point is to show how ordinary details such as locale, time zone, screen, battery, storage, keyboard languages, and other signals can become identifying when combined.
This is the part where things get a bit unsettling, since a device doesn’t need your email address, name, or exact location to recognize you r across apps and websites. A bundle of small device details can be enough to help create an identifiable fingerprint.
The scary bits are neatly organized
Loupe sorts readings into three tiers. Passive signals are visible to any app without a permission prompt, including things like locale, time zone, screen, battery, and more. Needs Permission covers data that triggers an iOS prompt, such as contacts, photos, location, and calendars. Advanced includes side-channel techniques such as URL-scheme probing and Keychain persistence across app reinstalls.
The App Store listing also mentions examples like identifying which popular apps are installed, the exact second a device was set up or erased, graphics checks through a hidden browser, and the name on a paired accessory, which can also reveal the owner’s name outright. Mysk’s previous works have found glaring issues with smartphone privacy, and their new app just shows how accessible your digital footprint actually is.
