What is the `ajs_user_id` Cookie?

Set by Segment (Twilio Inc. (Segment)). Expires after 1 year.

Purpose

Stores the identified user ID set via Segment's identify() call, linking analytics events to a known user.

Set once a user is identified. Requires consent as it enables cross-tool user tracking.

Cookie Details

Cookie Name	`ajs_user_id`
Service	Segment
Provider	Twilio Inc. (Segment)
Category	Analytics
Duration	1 year
Consent Required	Yes — 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 ajs_user_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

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

Other Segment Cookies

Cookie	Category	Duration
ajs_anonymous_id	Analytics	1 year

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