Participate in early testing for Storage Partitioning

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:

Make sure you are using Chrome Beta version 106 or higher.
Go to chrome://flags/#third-party-storage-partitioning.
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.