European Unified ID (EUID)

Leading consent-based, email-derived identity solution for GDPR-compliant programmatic advertising in Europe, backed by The Trade Desk

European Unified ID (EUID) is an open-source identity framework developed and governed by The Trade Desk, designed specifically for the European market as a privacy-compliant alternative to third-party cookies. Built on the same technical foundation as Unified ID 2.0 (UID2), EUID uses hashed and encrypted email addresses to create pseudonymous identifiers that enable addressable advertising while respecting GDPR and other European privacy regulations. Users must provide explicit consent before their email data is used, aligning with European legal requirements. EUID operates as a shared, interoperable identity layer across the open internet, allowing publishers, advertisers, and data partners to transact on a common identifier without relying on third-party cookies. The system is designed so that raw email addresses are never shared across the ecosystem — only encrypted tokens are passed between parties, with decryption keys managed through a secure operator model. Both open and private operator options are available, giving participants flexibility in how they integrate. In the AdTech ecosystem, EUID represents a significant industry effort to establish a durable, consent-based identity solution for a post-cookie European advertising landscape. It competes with other identity solutions such as ID5, LiveRamp's RampID, and Criteo's SPARROW, and has attracted adoption from major publishers, DSPs, SSPs, and data partners across Europe. The Trade Desk plays a central governance role, though the framework is designed to be open and interoperable across the broader industry.