Google published a blog post this week that drew less attention than it deserved, given that it fundamentally repositions the identity landscape for post-cookie programmatic advertising. The announcement: after third-party cookies are deprecated in Chrome, Google will not build or use alternate cross-site identifiers to track users across the web for advertising purposes.

This is not a minor technical clarification. It is a statement that Google is explicitly opting out of the email-hashed identity ecosystem — UID2, LiveRamp’s RampID, ID5, and the various other identity graph products that have been positioned as cookie replacements. Google is not joining that ecosystem. It is positioning against it, and it is doing so while developing its own browser-based cohort alternative (FLoC) that does not depend on cross-site identifiers.

The implications cascade through the identity vendor ecosystem, through publisher authentication investment decisions, and through the competitive structure of the post-cookie programmatic market.

What Google Actually Said

The blog post, authored by David Temkin, Google’s Director of Product Management for Ads Privacy and Trust, states the position clearly: “We will not build alternate identifiers to track individuals as they browse across the web, nor will we use them in our products.”

The key phrase is “alternate identifiers to track individuals across the web.” UID2 is built on hashed email addresses as a cross-site tracking identifier. RampID resolves user identity across sites through email matching and probabilistic methods. All of these are, by definition, alternate identifiers that track individuals across the web. Google is saying it will not use them.

This immediately raises a question about Google’s own products: Google Account sign-in, which provides identity across Google-owned properties (Gmail, YouTube, Google Search, Maps, Drive), is also an identifier that tracks users across properties. Google’s answer, implicit in its blog post and explicit in subsequent analyst calls, is that logged-in Google Account identity is a first-party relationship within Google’s ecosystem, not cross-site tracking in the same sense. The user chose to have a Google Account; Google Account data stays within the Google-owned and operated environment.

This distinction is real but conveniently favorable to Google’s competitive position. Google’s first-party identity ecosystem — covering Search, YouTube, Gmail, and the Google Display Network’s logged-in inventory — is vast. The ruling out of cross-site identifiers limits everyone else’s ability to build comparable reach while Google’s existing logged-in scale is unaffected.

What This Means for UID2

The Trade Desk’s UID2 was the identity solution that most directly positions as a cookie replacement at scale. Its mechanism — hashed email addresses passed through programmatic bid requests — is exactly the kind of cross-site identifier Google says it will not use.

UID2’s relevance after this announcement depends heavily on which DSPs and SSPs adopt it. Without Google — the largest DSP (DV360), the largest ad server (Google Ad Manager), and the largest exchange (Google AdX) — UID2 has a ceiling. Campaigns running through Google’s buy-side infrastructure will not be able to target UID2 audiences in the post-cookie environment. Publishers using Google Ad Manager will not be able to transact against UID2 signals through the Google stack.

The Trade Desk can run UID2-targeted campaigns through The Trade Desk’s own infrastructure and through SSPs that are not primarily Google-dependent. But the scale of the open web that Google’s infrastructure touches is substantial enough that a cookie replacement that Google will not use is, by definition, a partial replacement.

The Trade Desk’s CEO Jeff Green pushed back publicly, arguing that the logged-in web is large enough to support UID2 at meaningful scale and that Google’s position is itself an anticompetitive stance. The argument has merit: if Google simultaneously deprecates cookies and refuses to adopt the identity alternatives the rest of the ecosystem builds, it is advantaging its own first-party identity infrastructure.

The Competitive Map Has Split

Google’s announcement divides the identity landscape into two architecturally distinct camps.

The email-hashed identity camp (UID2, RampID, ID5, and similar): cross-site identifiers built on authenticated first-party data, primarily email addresses, used to track and target users across the open web. These are the solutions that publishers with authentication programs and DSPs like The Trade Desk are building toward. They will work in inventory that transacts outside of Google’s buy-side infrastructure.

The browser-side cohort camp (FLoC and its Privacy Sandbox descendants): interest-based targeting derived from in-browser computation, where cohort IDs replace individual identifiers. These are the solutions that Google is building toward and that will be available in Chrome regardless of whether publishers or DSPs adopt email-based identity.

These are not compatible approaches for the same inventory. A programmatic campaign run through The Trade Desk against UID2-authenticated publisher inventory will operate completely differently from a programmatic campaign run through DV360 against FLoC cohort signals. Post-cookie, media buying will not be a single unified ecosystem — it will be at minimum two distinct identity paradigms operating in parallel.

What This Means for Publisher Authentication Programs

Publishers who have invested in authentication programs under the assumption that email-based identity would become the dominant post-cookie signal need to re-evaluate that assumption in light of Google’s announcement.

The investment in authentication is not wasted — logged-in users provide first-party data signals that are valuable for contextual audience activation, direct deal pricing, and non-Google programmatic channels. But the revenue uplift from authenticated inventory in Google’s ecosystem is not the same as the uplift from authenticated inventory in UID2-compatible channels.

LiveRamp’s Authenticated Traffic Solution is specifically designed to enable authenticated publisher inventory to transact across multiple demand-side platforms, including The Trade Desk. The question publishers should ask is: what percentage of my programmatic demand flows through Google channels versus non-Google channels, and how does that distribution affect the ROI of my authentication investment?

For publishers that are heavily Google-stack dependent — using Google Ad Manager as their primary ad server and relying on Google’s demand through Open Bidding — the email-based identity value proposition is limited by Google’s explicit non-participation. For publishers with diversified demand relationships, including strong Prebid integrations and non-Google SSP relationships, authentication investment pays against a larger share of their total demand.

FAQ

Is Google’s position on alternate identifiers a legal requirement or a policy choice? It is a policy choice. Google is not legally prohibited from building or using hashed email identifiers in its products. The announcement reflects Google’s strategic positioning: it is investing in Privacy Sandbox browser-based targeting rather than email-based cross-site identity, and it is framing that choice as a privacy value statement. The UK’s CMA, which is scrutinizing the Privacy Sandbox for anticompetitive effects, is likely to examine whether Google’s simultaneous deprecation of cookies and refusal to support alternative cross-site identifiers constitutes market foreclosure.

Does Google’s position affect Google Analytics and Google Ads first-party remarketing? Google’s announcement specifically refers to cross-web tracking using alternate identifiers — tracking users across third-party sites. First-party remarketing in Google Ads — targeting users who have visited your website and who are matched against Google Account identity — is a different use case. Google has indicated that first-party data relationships, where users have directly interacted with an advertiser or publisher, remain permissible. The specific implications for various Google product features will become clearer as the Privacy Sandbox APIs develop.

If Google won’t use UID2, does UID2 have enough scale to be worth investing in? This depends entirely on your buying infrastructure. For programmatic campaigns run primarily or exclusively through Google’s buy-side stack (DV360, Google Ads), UID2 provides limited near-term value. For campaigns run through The Trade Desk, MediaMath, or other independent DSPs against inventory that transacts outside Google’s exchange, UID2 integration has meaningful scale potential. Most large brand programmatic programs use multiple DSPs, which means UID2 is valuable for the non-Google portion of the program even if it is inapplicable to Google’s channels.

What should we tell clients about the post-cookie identity landscape now? Be honest about the fragmentation. There is no single cookie replacement that works across all programmatic channels. Google’s environment will use browser-cohort signals. The independent ecosystem is moving toward email-based identity. Measurement and attribution will rely on modeled approaches for most non-Google channels. The programmatic media plan of 2023 will likely require explicitly different targeting and measurement strategies for Google channels versus independent channels, and planning for that bifurcation should begin now.