In email to developers, Google says it will soon cut off access to “Advertising IDs” when Android users opt out, instead showing developers a “string of zeros”
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Context & Ripple Effects
This is Google's answer to the identifier crackdown Apple started. In January, Google had already mapped out how Apple's IDFA changes would cut install-metric visibility and disrupt ad bidding — now it is imposing the same logic on its own platform: opted-out Android users will hand developers a string of zeros instead of an Advertising ID.
The move sits on top of a longer arc: Google's Chrome team proposed an anti-fingerprinting open standard back in 2019, so cutting off the device-level ad identifier while blocking workarounds has been the company's stated direction for two years.
First-order effects
- Android developers lose attribution and targeting signals for every user who opts out, with no replacement identifier — the same install-measurement and bidding disruption Google itself warned about for iOS.
- Advertisers buying Android inventory face shrinking addressable audiences for personalized ads, concentrated on whichever users have not toggled the opt-out.
Second-order effects
- Developers and ad networks pushed off the Advertising ID will test fingerprinting and other proxies, which collides directly with Google's own anti-fingerprinting standard — forcing the ecosystem toward whatever replacement API Google offers rather than self-made ones.
- Rival app stores and OEMs distributing Android variants gain a pitch to performance marketers: fewer privacy gates, more measurable installs.
Third-order effects
- The endgame Google sketched is bringing Privacy Sandbox to Android — retiring per-user identifiers entirely in favor of platform-operated cohort APIs, making the OS owner the gatekeeper of all ad targeting on mobile.
- If both major mobile platforms converge on this model, ad-tech intermediaries without first-party data or platform partnerships get squeezed out of the measurement layer structurally, not just technically.
The trend: Mobile platforms are replacing per-device advertising identifiers with their own privacy APIs, with each announcement pressuring the other to move faster.