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Do Temporary Session Identifiers (Session IDs) Require Consent Under GDPR?

A common question around privacy-compliant analytics is whether temporary Session IDs fall under “tracking technologies” that require user consent.
The short answer: it depends on how the Session ID is implemented.

A temporary Session ID requires consent if:

  • It is stored in a cookie or similar persistent storage
  • It can be used to recognize a user over time
  • It can be combined with other identifiers to reconstruct a profile
  • It is used for tracking across multiple domains

In these cases, the Session ID becomes a personal identifier, making consent mandatory under:

  • GDPR
  • ePrivacy Directive
  • Local guidelines (CNIL, AEPD, ICO…)

Regulators such as CNIL (France) and AEPD (Spain) explicitly allow “cookie-less session identifiers” for audience measurement, as long as they meet strict conditions:

  • Used exclusively for audience measurement (no marketing / profiling)
  • No cross-site tracking
  • Not persistent → disappears after the browser session ends
  • Not stored in cookies or localStorage
  • Cannot be combined with other identifiers to re-identify the user
  • No fingerprinting techniques

If all these requirements are met, the Session ID is considered non-identifying, and consent is not required.

How SealMetrics Ensures Compliance

SealMetrics provides two measurement modes to adapt to different privacy levels:

1. Session ID Mode

✔ Temporary Session IDs
✔ Fully compliant with CNIL & AEPD consent exemptions
✔ No persistence
✔ No personal identification

Session IDs are used only within the active session to group hits — never to track or identify users.

2. Super-Privacy Mode (Isolated Hits)

No Session IDs at all
✔ No cookies
✔ No identifiers
✔ Maximum anonymity

This mode guarantees absolute compliance with GDPR, ePrivacy, and the strictest interpretations of privacy law.

Summary

ScenarioRequires Consent?Why
Session ID stored in a cookieYesPersistence = identification
Temporary ID without cookiesNoCannot identify the user
Cross-site session trackingYesConsidered profiling
Isolated hits (no Session ID)NoNo identifiers at all

SealMetrics ensures that all tracking—Session-based or Isolated—remains fully compliant with GDPR and ePrivacy, without compromising your analytics.

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