Epsilon

Overview

Epsilon is a subsidiary of Publicis Groupe and one of the largest data-driven marketing companies in the world. Its technology stack spans loyalty program management, email campaign delivery, and programmatic advertising through its CORE ID identity graph, which links consumer identities across devices and channels. Epsilon's reach is extensive — it maintains one of the industry's largest consumer databases, with data on hundreds of millions of individuals.

What This Script Does

Epsilon's client-side presence typically involves tracking pixels and JavaScript tags that serve several functions:

Data Collection Tags

Scripts loaded from domains like epsilon.com, conversant.com (Epsilon's ad tech brand), and dtci.com collect detailed behavioral data including:

• Pages viewed and time spent on each page
• Product interactions (views, add-to-cart, purchases)
• Search queries entered on the site
• Click patterns and scroll behavior

Identity Resolution

Epsilon's CORE ID system attempts to match website visitors to its identity graph. The scripts set cookies to maintain persistent identifiers:

• _epid — Epsilon persistent identifier cookie (expires after 13 months)
• _epuid — hashed user identifier for cross-site matching
• Third-party cookies on conversant.com and epsilon.com domains for cross-site identification (being phased out in some browsers)

Audience Activation

The collected behavioral data feeds into Epsilon's demand-side platform (DSP) for programmatic ad targeting. Data is used to build audience segments, create lookalike models, and deliver personalized ads across display, video, and connected TV channels.

Loyalty Program Integration

For retailers using Epsilon's loyalty platform, additional scripts may track purchase completions and link transactions to loyalty accounts.

Consent & Compliance

Epsilon is classified as marketing. Its scripts perform cross-site user identification, behavioral profiling, and advertising audience construction — all activities that require explicit consent under GDPR. The use of third-party cookies and cross-site identity graphs makes this unambiguously a marketing/advertising technology.

Under the ePrivacy Directive, Epsilon's persistent tracking cookies require prior informed consent. They are not necessary for any service the user has requested and serve the operator's advertising interests.

Under CCPA/CPRA, Epsilon's data collection likely constitutes both "selling" (exchanging personal information for monetary consideration via ad targeting) and "sharing" (making data available for cross-context behavioral advertising). Sites must honor opt-out requests and provide clear disclosure. Epsilon participates in the IAB's Transparency and Consent Framework and the DAA's AdChoices program, but these industry mechanisms do not replace the legal requirement for consent in jurisdictions that mandate it.

Should You Block This Without Consent?

Yes. Epsilon's scripts perform cross-site tracking and behavioral profiling for advertising purposes. They must be blocked until the user provides explicit consent for marketing cookies. No core website functionality depends on Epsilon's tags.