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How to Prepare for Chrome’s 2024 Third‑Party Cookie Phase‑Out

8 March 2026 by
Suraj Barman

Third‑Party Cookie Phase‑Out in Chrome 2024

Third‑party cookies are browser‑stored data set by domains other than the page the user is visiting. Chrome will gradually disable them in 2024, moving from a 1% test group in Q1 to full rollout by Q3, reshaping how tracking and cross‑site state are handled.

Understanding Third‑Party Cookies and Their Risks

These cookies enable data sharing across sites, which can power legitimate services like single sign‑on but also fuel extensive user profiling.

  • Set via the Set-Cookie header on cross‑site resources.
  • Allow aggregation of browsing history across unrelated domains.
  • Commonly used for ad targeting and analytics.
  • Can be classified as tracking cookies when used to build detailed user profiles.
  • Subject to privacy regulations such as GDPR and CCPA.

Current Browser and Regulatory Landscape

Firefox and Safari already block most third‑party cookies by default, while Chrome has been slower due to its advertising ecosystem.

  • Firefox offers per‑site toggles in its privacy settings.
  • Safari relies on the Storage Access API for limited exceptions.
  • Edge mirrors Chromes default behavior, keeping cookies enabled.
  • Regulators require clear consent mechanisms and data‑access rights.
  • Browser vendors balance user privacy with legacy web functionality.

Chromes Phased Deprecation Plan

Google will introduce the change in stages, giving developers time to adapt.

  • Q1 2024: 1% of users experience blocked third‑party cookies for testing.
  • Q2 2024: Incremental increase to 25% of users.
  • Q3 2024: Target of 100% rollout, pending competition review.
  • Privacy Sandbox APIs replace many use cases (e.g., FLEDGE, Topics).
  • Developers receive official guidance and test flags.

Migration Strategies for Developers

Switching away from third‑party cookies requires alternative storage and identity solutions.

  • Adopt Storage Access API where cross‑site access is still needed.
  • Use first‑party cookies combined with server‑side session linking.
  • Leverage Web Storage (localStorage, sessionStorage) for client‑side state.
  • Consider IndexedDB for larger, structured data.
  • Implement privacy‑preserving identifiers from the Privacy Sandbox.

Tools and Resources

Google and the community provide utilities to audit and transition your sites.