What is the SID cookie?
SID is a first- and third-party HTTP cookie set by Google on .google.com. It belongs to a larger family of Google cookies (alongside HSID, SSID, APISID, SAPISID) that work together to keep a Google user signed in and support related account functions.
On a website that isn't owned by Google, the SID cookie can appear indirectly when the site embeds Google services (such as Google Ads, ads served through Google, YouTube embeds, Google sign-in buttons, or other Google widgets) that communicate with Google domains and may set such cookies on .google.com.
What data it stores
According to Google's public documentation, SID stores an encrypted, digitally signed identifier unique to the user's account or session, used for authentication and security purposes. The exact value format isn't documented in detail publicly and may vary; it is not a simple human-readable random value.
Data associated with this cookie is sent to Google's servers (the .google.com domain and related Google infrastructure), not to the hosting website. Site owners have no access to the cookie's contents, only to the fact that it is set by an embedded Google script.
What it is used for
For Google, SID helps identify and authenticate signed-in users, prevent fraudulent use of login credentials, and store security-related preferences. Combined with related cookies (HSID, SSID), it contributes to profiling a user's online behavior for advertising purposes.
For a website embedding Google services, this cookie provides no direct visible functionality, but it is a side effect of using Google tools (ads, analytics, embeds) and can influence the relevance of ads shown to visitors elsewhere in the Google network.
Does it require consent?
Under CookieFix's classification, SID is a marketing (advertising/tracking) cookie. Under Romania's Law 506/2004 (transposing the ePrivacy Directive) and the GDPR, this type of cookie requires prior user consent before being placed, since it involves tracking and profiling for advertising purposes.
- The cookie must be clearly listed in the site's cookie policy, including provider (Google), purpose, and duration.
- The script that triggers this cookie (typically a Google Ads tag, embed, or Google sign-in button) should be blocked by default until explicit consent is given.
- Romania's data protection authority (ANSPDCP) can sanction sites lacking valid consent for marketing cookies.
How to block or delete SID
A visitor can delete or block this cookie from browser settings (Chrome, Firefox, Edge, Safari – site cookie management sections), or use private/incognito browsing. Deleting the SID cookie may sign the user out of their Google account on that device.
For site owners, the correct approach is to prevent Google scripts capable of setting this cookie (ads, embeds, sign-in buttons) from running automatically on page load. A CMP like CookieFix can automatically block these scripts until the visitor consents to the marketing category, preventing the cookie from being set without authorization.
Frequently asked questions
It's an HTTP cookie set on .google.com, used by Google for authentication, security, and indirectly for advertising profiling.
Yes, since it's classified as marketing/tracking, it requires the user's prior consent under Romania's Law 506/2004 and the GDPR.
Its typical duration is around 2 years from being set or last updated.
By blocking Google scripts (ads, embeds, login widgets) until consent is given, using a CMP that manages cookie categories.