Partition network state by the network partition key (which consists of top frame site and possibly frame site), to protect against cross-site tracking through the use of side channels. "Network State" here includes connections (H1, H2, H3, websocket), the DNS cache, ALPN/H2 support data, TLS/H3 resumption information, Reporting/NEL configuration and uploads, and Expect-CT information. Explainer:


Cross-site tracking is a major privacy concern for users. This is a necessary part of addressing the problem.


Editor's draft

Status in Chromium


In developer trial (Behind a flag) (tracking bug) in:

  • Chrome for desktop release 89
  • Chrome for Android release 89

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.


Intent to Prototype url

Intent to Prototype thread


Note that the tracking bug covers more than this feature covers.

Last updated on 2021-04-24