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What is the _ym_isad Cookie?

Set by Yandex Metrica (Yandex LLC). Expires after 2 days.

Purpose

Used by Yandex Metrica to determine whether the visitor has an ad blocker enabled.

Short-lived helper cookie for Yandex's analytics; still requires consent.

Cookie Details

Cookie Name_ym_isad
ServiceYandex Metrica
ProviderYandex LLC
CategoryAnalytics
Duration2 days
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 _ym_isad 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 Yandex Metrica 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 (Yandex LLC), and expiry (2 days).
  4. Sign a DPA — ensure you have a Data Processing Agreement with Yandex LLC covering their use of data collected via this cookie.
  5. Verify it works — in an incognito browser, reject cookies and confirm _ym_isad is not set.

Other Yandex Metrica Cookies

CookieCategoryDuration
_ym_uidAnalytics1 year
_ym_dAnalytics1 year

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