FewCookies

Cookie glossary · Marketing

What is the afUserId cookie?

Unique user identifier set by the AppsFlyer web SDK (first-party cookie) for campaign and conversion attribution. It is set by AppsFlyer and classified as "Marketing". Requires consent.

At a glance

Provider AppsFlyer
Category Marketing
Consent required? Yes
Typical domain Varies (first-party)

How FewCookies handles this cookie

FewCookies recognises afUserId from our database of 1,300+ known cookies and classifies it automatically as "Marketing". The free check tells you whether this cookie is detected on your site and whether your banner handles it correctly — an instant, surface-level check, no account needed.

Check your site for free →

Frequently asked questions

Do you need consent for the afUserId cookie?

Yes. afUserId is a "Marketing" cookie, so it is not strictly necessary. Under the ePrivacy Directive (2002/58/EC) and Romania's Law 506/2004, you must obtain the visitor's explicit consent before setting it.

What does the afUserId cookie do?

Unique user identifier set by the AppsFlyer web SDK (first-party cookie) for campaign and conversion attribution.

Who sets the afUserId cookie?

The afUserId cookie is associated with AppsFlyer and is classified as marketing.