What is the csync cookie?
Synchronizes unique user identifiers between Equativ and its third-party demand partners to facilitate cross-platform tracking and targeted programmatic advertising.
Table of Contents
About the csync cookie
| Vendor | Equativ |
|---|---|
| Cookie Domain | smartadserver.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Advertising & Paid Media |
| Consent Category Consent Category The consent category this cookie most commonly falls under across sites we scan, normalized into four standard categories. Learn more | Targeting & Advertising |
| Prevalence | Very Common |
| Popularity Popularity Popularity is calculated from our dataset of 4.5B+ cookies analyzed across hundreds of millions of web pages. Learn more | Found on 11.7% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 30 days |
| Party Type Party Type Whether the cookie is first-party or third-party. Learn more | 3rd-Party |
| Risk Level Risk Level Rates how sensitive the data stored by this cookie is (High, Medium, or Low) based on data classification and distribution. Learn more | High |
| Vendor Privacy Policy | https://equativ.com/cookie-policy/ |
| Vendor Website | https://equativ.com |
What is the purpose of the csync cookie?
The csync cookie is a third-party tracking cookie set by Equativ (formerly Smart Adserver, which rebranded in 2022). It operates as a user synchronization (cookie syncing) mechanism within programmatic advertising.
When a user interacts with a page or ad, Equativ's platform drops this cookie to store a proprietary unique identifier (or match ID). This identifier is then shared across different Demand-Side Platforms (DSPs), Data Management Platforms (DMPs), and Ad Exchanges so that the user is consistently recognized across the ecosystem. This cross-platform matching allows advertisers to bid on real-time auctions more effectively, measure performance, frequency cap campaigns, and display retargeted or highly personalized ads.
What are the Privacy Risks of the csync cookie?
Risk Level: High
The cookie is explicitly designed for cross-site user tracking and programmatic audience profiling. It shares persistent, pseudonymous identifiers with multiple third-party demand partners (DSPs, exchanges, and data partners), directly supporting behavioral advertising and real-time bidding. Because the same-identifier is propagated across many downstream recipients with limited end-user transparency, the privacy exposure is treated as High for site operators evaluating approval.
How to Remove the csync cookie from a Website
Website administrators can remove this cookie by eliminating Equativ (Smart Adserver) ad tags, the smart.js library, or related Prebid.js integration from the website. If the Equativ integration is retained but the administrator wishes to stop the cookie sync process, they can remove the standalone CookieSync.html iframe (from csync-global.smartadserver.com) from the page source or configure their Prebid.js/SSP setup to disable automatic user syncing for Equativ's bidder adapter.