Browser security
Compatibility & evidence
Browser privacy

Partitioned cookies

Stores selected cross-site cookies in a partition keyed by the top-level site.

Support in current browsers

Checked against the current browser versions recorded in MDN browser data 8.1.5.

BrowserMinimumOutcomeReason
Chrome155WorksEvery required mapped BCD feature is available without a recorded qualification.
Edge154WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox157WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari27WorksEvery required mapped BCD feature is available without a recorded qualification.
Chrome for Android155WorksEvery required mapped BCD feature is available without a recorded qualification.
Firefox for Android157WorksEvery required mapped BCD feature is available without a recorded qualification.
Safari on iOS27WorksEvery required mapped BCD feature is available without a recorded qualification.
Android WebView155WorksEvery required mapped BCD feature is available without a recorded qualification.
Samsung Internet30.0WorksEvery required mapped BCD feature is available without a recorded qualification.
The release trace

How support changed

Each segment groups recorded releases with the same result. Gaps between recorded versions are not filled in. This is support at each release, rather than the planner’s check of every release above a minimum.

Chrome

http.headers.Set-Cookie.Partitioned
  1. 1 – 113112 recorded releases
    Not supported
  2. 114 – 15542 recorded releases
    Works

Edge

http.headers.Set-Cookie.Partitioned
  1. 12 – 11341 recorded releases
    Not supported
  2. 114 – 15441 recorded releases
    Works

Firefox

http.headers.Set-Cookie.Partitioned
  1. 1 – 140143 recorded releases
    Not supported
  2. 141 – 15717 recorded releases
    Works

Safari

http.headers.Set-Cookie.Partitioned
  1. 1 – 18.350 recorded releases
    Not supported
  2. 18.41 recorded release
    Works
  3. 18.5 – 26.14 recorded releases
    No longer supported
    • Support was removed in 18.5
  4. 26.2 – 276 recorded releases
    Works

Chrome for Android

http.headers.Set-Cookie.Partitioned
  1. 18 – 11389 recorded releases
    Not supported
  2. 114 – 15542 recorded releases
    Works

Firefox for Android

http.headers.Set-Cookie.Partitioned
  1. 4 – 140124 recorded releases
    Not supported
  2. 141 – 15717 recorded releases
    Works

Safari on iOS

http.headers.Set-Cookie.Partitioned
  1. 1 – 18.347 recorded releases
    Not supported
  2. 18.41 recorded release
    Works
  3. 18.5 – 26.14 recorded releases
    No longer supported
    • Support was removed in 18.5
  4. 26.2 – 276 recorded releases
    Works

Android WebView

http.headers.Set-Cookie.Partitioned
  1. 1 – 11384 recorded releases
    Not supported
  2. 114 – 15542 recorded releases
    Works

Samsung Internet

http.headers.Set-Cookie.Partitioned
  1. 1.0 – 22.044 recorded releases
    Not supported
  2. 23.0 – 30.08 recorded releases
    Works

BCD 8.1.5 · catalogue 2.3.0. Source corrections can change this trace without a new browser release.

What this feature can and cannot do

Helps protect against

  • Cross-site tracking
  • Unpartitioned third-party state sharing

Does not guarantee

  • All browser fingerprinting
  • First-party tracking
  • Authorisation flaws

What you need before using it

  • Secure cookies
  • A design that tolerates partitioned state

Fallback to keep in place

Minimise third-party state and avoid relying on cross-site cookies when partitioning is unavailable.