Participate in early testing for Storage Partitioning

How to check if your site is affected by Storage Partitioning.

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Translated to: 日本語

To improve privacy, Chrome is changing how storage and communication APIs will behave in future releases. Read more about the upcoming change in Storage Partitioning.

The initial implementation has been available behind a flag in Chrome 105, since July 2022. Starting in Chrome Beta 106, from September 2022, the new implementation (which includes Cache Storage partitioning) is available for testing. The latest features and bug fixes will land in Chrome Canary first, so consider using Canary for continued testing.

This change should not affect the most common use cases where your app only uses storage in a first-party context, but we recommend testing to ensure that your applications will continue to work as they do today. If you interact with, or rely on storage in iframes, there's a higher chance the change may impact you.

How to test Storage Partitioning

To try Storage Partitioning out:

  1. Make sure you are using Chrome Beta version 106 or higher.
  2. Go to chrome://flags/#third-party-storage-partitioning.
  3. Enable the "Experimental Third-party Storage Partitioning" flag.

Participate in early testing and report bugs to help the Chrome team identify and fix any unexpected behavior before the stable launch.

What is Storage Partitioning

To prevent certain types of side-channel cross-site tracking, Chrome is partitioning storage and communications APIs in third-party contexts (see the explainer for more details).

Historically, storage has been keyed only by origin. This means that if an iframe from example.com is embedded on a.com and b.com, example.com could learn about your browsing habits for those two top-level sites by storing and successfully retrieving an ID from storage. With third-party Storage Partitioning enabled, the storage for example.com will exist in two different partitions, one for a.com and the other for b.com. Storage partitioning prevents an embed from joining your visits to either site.

The following storage and communication APIs are partitioned when enabling the "Experimental Third-party Storage Partitioning" flag:

The following APIs are under active development, and will be partitioned before shipping to stable:

  • Blob URL
  • Clear-Site-Data header

When will this feature be launched by default

We are hoping to begin the feature launch in early 2023, depending on stability and compatibility. Testing third-party storage partitioning now and filing bugs will help Chrome get feedback from the ecosystem to ensure developers and site owners have the support they need.

Reporting bugs

The best way to give feedback is to file a new issue, either with a link to a publicly accessible URL or a reduced test case.

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