Cookieless advertising

"Cookieless" became a buzzword when browsers began blocking third-party cookies: Safari and Firefox did so years ago, and for a long time Chrome planned to. The phrase covers everything the industry built to work without them.

The toolkit includes first-party data and publisher logins, contextual targeting, email- and login-based identifiers like Unified ID 2.0 and RampID, seller-defined audiences, clean rooms, server-side conversion tracking, and aggregated measurement such as marketing mix modeling and incrementality tests. Google's Privacy Sandbox was meant to be a major pillar until Google announced in October 2025 that it would retire most of it.

In 2026 the picture is mixed: Chrome still supports third-party cookies, so a large share of open-web traffic remains addressable, while Safari, Firefox and iOS apps without App Tracking Transparency consent are effectively cookieless. "Cookieless" is also not the same as "privacy-safe": replacing cookies with other persistent identifiers or device fingerprinting can raise the same concerns. Consent requirements apply regardless of the technique.

Think of it like this

Cookieless advertising is like a city planning for life after a major bridge closes, building ferries, tunnels and new routes; the bridge may stay open longer than expected, but the new routes are useful anyway.

An example

A publisher in Australia finds that 45% of its traffic (Safari and iOS) carries no third-party cookie, so it sells that inventory with contextual segments and a login-based ID, recovering most of the CPM gap.