Understanding Third‑Party Cookies, SameParty, and Chrome's CHIPS Partitioned Cookies

Hello, I am ConardLi , and today we continue discussing Cookie , focusing on third‑party Cookie issues.

Third‑party Cookie s allow services to track users across unrelated top‑level sites, a practice known as cross‑site tracking.

Browsers are restricting this behavior: Safari has already blocked third‑party Cookie s completely, and Chrome has announced it will deprecate them within the next two years.

There is no mature industry‑wide solution yet; the new SameParty attribute added to Cookie s last year can share cookies among domains owned by the same entity, but its usage is limited and complex.

A common scenario: a third‑party chat service support.chat.example embedded via iframe on retail.example relies on Cookie s to store user interaction history. Without third‑party Cookie s, the chat service would need to depend on first‑party identifiers or insecure JavaScript bridges, increasing development cost and risk.

To address this, Chrome proposes CHIPS (Cookies Having Independent Partitioned State), which introduces a Partitioned attribute, allowing developers to store Cookie s in separate per‑site “cookie jars”.

Chrome describes CHIPS as a crucial step toward a future without third‑party Cookie s.

When a Cookie is marked Partitioned , it is saved in a special partitioned jar and is only sent when the top‑level site matches the partitioning context (e.g., site A embedding site C via iframe ).

If a user later visits another top‑level site B that also embeds C , the partitioned Cookie set under A will not be accessible, preserving privacy.

Chrome will enable CHIPS for testing in versions 100‑103; developers can enable it locally in Chrome Canary via the flag chrome://flags/#partitioned-cookies .

Full proposal: https://github.com/WICG/CHIPS

Like SameParty , CHIPS is one of several proposals to solve the third‑party Cookie problem, and its eventual adoption across browsers remains to be seen.