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What is the datafast_visitor_id Cookie?

Set by Datafa.st (Datafa.st). Expires after 1 year.

Purpose

Persistent visitor identifier used by Datafast to attribute revenue and conversions to the correct marketing channel across sessions. Passed as metadata to Stripe Checkout to link payments to traffic sources.

Required when using the default Datafast script (script.js). Consent is required under GDPR. Datafast also offers a cookieless script (script.cookieless.js) that uses session storage and a daily-rotating hash instead — typically not requiring a cookie banner.

Cookie Details

Cookie Namedatafast_visitor_id
ServiceDatafa.st
ProviderDatafa.st
CategoryAnalytics
Duration1 year
Consent RequiredYes — requires explicit opt-in

Category: Analytics

Analytics cookies help website owners understand how visitors interact with websites by collecting and reporting information anonymously. Consent is required under GDPR.

GDPR Requirements

Under GDPR and the ePrivacy Directive, the datafast_visitor_id cookie requires explicit user consent before it can be set. This means:

  • The cookie must not be set when a user first visits your site — not even for a fraction of a second
  • A consent banner must be displayed, and the user must actively accept analytics/marketing cookies
  • If the user rejects or ignores the banner, this cookie must remain blocked
  • The cookie must be listed in your cookie policy with its name, purpose, and retention period
  • Users must be able to withdraw consent at any time, which must also remove or invalidate this cookie

How to Handle This Cookie

  1. Block it by default — configure your Consent Management Platform (CMP) or tag manager to prevent Datafa.st from loading until the user accepts analytics cookies.
  2. Include it in your consent categories — map it to the "Analytics" category in your CMP configuration.
  3. List it in your cookie policy — document the cookie name, purpose, provider (Datafa.st), and expiry (1 year).
  4. Sign a DPA — ensure you have a Data Processing Agreement with Datafa.st covering their use of data collected via this cookie.
  5. Verify it works — in an incognito browser, reject cookies and confirm datafast_visitor_id is not set.

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