Major Browser Vendors Announce Draft Standard to Phase Out Third-Party Tracking Cookies

16 September 2026

Google Chrome will begin a 1% testing period in Q1 2024 to deprecate default access to third-party cookies, joining Firefox and Safari in the move. A draft standard proposed by a W3C group and supported by major browser vendors outlines a phased approach to phase out these tracking cookies, while an IETF document suggests using partitioned cookies to limit cross-site data collection and sharing.

The draft standard, which has been endorsed by the W3C Technical Architecture Group, proposes a phased approach to deprecating third-party cookies, while recognizing the ongoing need for cross-site use cases like authentication. The document states that while the group "recognizes that stringent implementation of cross-site tracking will negatively impact some trackers, advertisers, and publishers," it believes that "privacy is a fundamental principle of the web."

Chrome's move follows a 2020 announcement by Google that it intended to phase out third-party cookies in two years, in favor of the company's own Privacy Sandbox initiative. While some objections from UK competition regulators delayed full rollout, Google is now proceeding with a 1% testing phase in Q1 2024, with a broader phase out planned for Q3 2024.

The IETF document, which defines a new "Partitioned" cookie attribute, aims to limit a cookie's scope to the same top-level site from which it was set, rather than allowing it to be read by any site that issues the same cookie. The proposed attribute is still in draft form and has not yet been finalized or implemented.

Browser makers and privacy advocates have been incrementally moving to limit third-party cookie tracking in recent years, on the basis that these cookies are used by advertisers and trackers to follow a user's activity across the internet, without their consent. Apple's Safari browser already restricts cookies, and Mozilla's Firefox version 3 introduced a cookie-blocking feature, which has since been expanded.

While some groups have pushed back on the deprecation, saying it harms innovation in advertising and online publishing, others have praised the direction as a long-overdue step for protecting user privacy. Tracking and website analytics firms will likely need to diversify their business models, while consolidating their user databases.

The new standard, with its phased approach and browser vendor support, suggests that browsers may become increasingly privatized, forcing the ad and data industries to refocus on more freely consented and targeted user tracking. The practical effects of the changes on website owners, online shoppers, and the broader app ecosystem are however still being studied.