Visitor identification

Every identification returns a visitor_id: a stable identifier for the device, resolved by the server. The same device returns the same visitor ID on its next visit, whether or not it kept its cookies.

The visitor ID

• Twenty letters and digits, such as X9pL2mRc7KvT4bQw8NdF. Treat it as an opaque string.
• Issued by Fingerly and never derived from the device's data, so it reveals nothing about the device.
• Scoped to your organization. The same device on another customer's site has a different visitor ID. Visitor IDs cannot be used to follow people across companies.
• The same across your development, staging and production keys.
• Always present on a successful identification.

The ID is designed to survive the changes devices go through: browser and operating system updates, new fonts, a different monitor, travel between networks.

Visitor confidence

visitor_confidence says how the ID was reached, from 0 to 100.

New visitors

visitor_is_new is true the first time your organization sees a visitor. Use it for new-account and first-purchase decisions, such as whether a welcome offer should apply.

When a device cannot be identified

Some browsers and clients give away almost nothing, whether through hardened privacy settings or deliberately. When there is too little to identify anyone, the response has identifiable: false:

• A fresh visitor ID is issued each time, so these clients appear as a stream of new visitors. Do not count them as returning or unique.
• The request is still scored, and the fingerprint_suppressed signal is added.
• A production request that is not identifiable costs $0.0005 instead of $0.003.

Using visitor IDs