What is the _ym_isad cookie?
_ym_isad is a cookie placed by Yandex Metrica, the web analytics service developed by Yandex, commonly used as an alternative to Google Analytics on many websites, including across Romania and Eastern Europe.
The cookie appears in the visitor's browser as soon as the Yandex Metrica script (mc.yandex.ru or similar) loads and runs on the page, whether the site owner installed the code directly or through a tag manager.
What data it stores
The cookie's value is typically a short numeric code, used internally by Yandex Metrica to signal whether an ad-blocking tool was detected in the visitor's browser. The exact value format may vary and is not documented in detail publicly by Yandex.
The data collected through this cookie, together with other session information, is sent to Yandex Metrica's servers for processing and statistical aggregation.
What it is used for
The main purpose is to adjust the traffic statistics shown in Yandex Metrica reports by accounting for visitors who block ads, since these visitors may behave differently or certain scripts may fail to load fully for them.
For the site owner, this information contributes to a more accurate picture of actual visitor numbers and how they interact with the page, without serving any content personalization or targeted advertising purpose.
Does it require consent?
Under CookieFix's classification, _ym_isad falls under the statistics (analytics) category. As an audience-measurement cookie that is not strictly necessary for the site's technical operation, it falls under the ePrivacy Directive (2002/58/EC, transposed in Romania via Law 506/2004) and requires the visitor's prior consent, consistent with GDPR's lawful processing principles.
- Site owners must disclose this cookie in their cookie policy, listing the provider (Yandex Metrica) and duration (approx. 2 days).
- The Yandex Metrica script should not load before the visitor has consented to the statistics category.
- Data protection authorities (such as Romania's ANSPDCP) can sanction sites that lack valid consent for analytics cookies.
How to block or delete _ym_isad
A visitor can delete or block _ym_isad manually from browser settings (Chrome, Firefox, Edge, etc., under cookies and site data), or use tracking/ad-blocking browser extensions.
For site owners, a CMP such as CookieFix automatically blocks the Yandex Metrica script from loading until the visitor has given consent for the statistics category, preventing this cookie from being set prematurely and reducing compliance risk.
Frequently asked questions
It's a technical cookie used by Yandex Metrica to flag whether the visitor's browser has an active ad blocker, a signal used when calculating traffic statistics.
Its typical duration is about 2 days, after which it expires automatically from the browser.
It does not store direct identification data, but it is part of the Yandex Metrica analytics cookie set and requires consent under GDPR/ePrivacy rules.
Yes, as a statistics cookie it must be disclosed in the cookie policy and only loaded after the visitor has given consent.