What is the viewer_token cookie?
This cookie is an advertising identifier used by LoopMe to track users across websites, report on ad performance, and control the frequency of ads shown.
Table of Contents
About the viewer_token cookie
| Vendor | LoopMe |
|---|---|
| Cookie Domain | loopme.me |
| 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 11.5% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 29 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://legal.loopme.com/privacy-center |
| Vendor Website | https://loopme.com |
What is the purpose of the viewer_token cookie?
The viewer_token cookie is a third-party tracking identifier set by LoopMe (majority-owned by Mayfair Equity Partners since 2022). LoopMe operates as a programmatic advertising platform, utilizing artificial intelligence to optimize ad delivery and campaign performance. According to the vendor's official privacy documentation, this specific cookie functions as an advertising identifier to record which advertisements have been displayed to a user. This enables the platform to apply frequency capping, ensuring that visitors are not shown the same ads repetitively.
Additionally, the cookie functions as a persistent identifier that ties browsing events and ad interactions to a specific user across multiple publisher websites. The cookie is observed being set on LoopMe's cookie-sync endpoint (csync.loopme.me), where it is matched with partner identifiers from exchanges such as Amazon Advertising, PubMatic, and others. LoopMe uses this cross-site data to measure the overall effectiveness of campaigns, report performance metrics back to advertisers, and build interest-based profiles to enable the delivery of targeted advertising across the broader programmatic ecosystem.
What are the Privacy Risks of the viewer_token cookie?
Risk Level: High
This cookie acts as a persistent cross-site tracking identifier used for interest-based advertising within the programmatic ecosystem. It is set during cookie-syncing between LoopMe and multiple advertising partners (for example Amazon Advertising and PubMatic), which is the mechanism used to match a user's identity across different companies and enable cross-site profiling.
Because the identifier is shared with third-party ad partners to support targeting and measurement, it carries a high privacy risk and typically requires explicit user consent under regulations such as the GDPR and CPRA. The observed consent-category tagging on real sites ('Sale and Sharing', 'Targeting Cookies', 'Advertising Cookies') is consistent with this high-risk, targeting-and-advertising classification.
How to Remove the viewer_token cookie from a Website
Website administrators who wish to remove the viewer_token cookie must locate and remove the LoopMe tags, pixels, cookie-sync (user-match) calls, or integration scripts from their website's source code or tag management system. If LoopMe is deployed indirectly through a supply-side platform, ad exchange, or header-bidding wrapper, administrators must remove LoopMe from the list of approved partners or disable the LoopMe adapter or user-sync in the wrapper's or platform's configuration. Because this cookie is set as part of LoopMe's user-matching process, it cannot be suppressed independently without removing or disabling the LoopMe integration that triggers it.
This definition was last reviewed on August 19, 2026. ObservePoint regularly reviews these definitions to ensure our customers have the most up to date information about the cookies on their websites.