Question 1

Does a fingerprint survive a cookie clear, incognito, or a VPN?

Accepted Answer

Yes. The fingerprint is computed from what the device is rather than from anything stored on it, so clearing cookies and local storage does not reset it, and a private window produces the same value. A VPN changes the IP address and nothing about the device, so the ID holds. It does change the network signals we weigh next to it, which is exactly why the IP is an input and not the identity.

Question 2

How is this different from a fingerprinting library like FingerprintJS?

Accepted Answer

A fingerprinting library hands you a visitor ID and stops there. You still build the device graph, decide what counts as too many accounts on one device, and ship the enforcement. Rupt returns the identity along with the history behind it: the linked accounts, the risks that fired, and the challenge that verifies the person. The part you were going to build yourself is already there.

Question 3

Does it work inside mobile apps?

Accepted Answer

Yes, through native iOS and Android SDKs. Native apps get a stronger anchor than the web does. iOS uses the identifier for vendor, Android uses the platform identifiers Google's guidelines allow, and both can tell you whether the device is jailbroken, rooted, running in an emulator, or sitting under a debugger. Same API, and the same account history behind your website and your app.

Question 4

Is device fingerprinting privacy compliant?

Accepted Answer

Fraud prevention is named as a legitimate interest under GDPR recital 47, which puts it on different footing from cross-site advertising. Rupt is first party and single service: it answers whether this device has been on your product before and what it did there, and it does not follow anyone around the rest of the web. We are happy to walk your privacy team through exactly what is collected.

Question 5

What happens when a fingerprint drifts?

Accepted Answer

Fingerprints move a little as browsers update and fonts get installed, which is why the device ID sits above the fingerprint instead of being the fingerprint. One layer changing does not break the match, because the remaining layers still agree and the device keeps its history. Drift measures under half a percent over 30 days, and on commodity hardware a match is corroborated with network and account signals before two devices are ever merged.

Question 6

How long does it take to integrate?

Accepted Answer

Most teams ship in a day. Drop in the SDK, call it where you already know who the user is, and read the device ID off the response. Mobile is the same shape with the iOS or Android SDK. If you already run Rupt, you have this today.

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Stable fingerprints for every device.

Device and browser fingerprints that survive cookie clears, incognito, and browser updates. One API across web, iOS, and Android.

An identity that holds still while everything around it changes.

One ID, every browser.

Drift-resistant browser fingerprints.

Trust that builds over time.

One API across web, iOS and Android.

Web, through the JS SDK

iOS, through the native SDK

Android, through the native SDK

Questions teams ask about device fingerprinting:

Find out how many devices are really behind your accounts.