Site A

This demo walks you through how partitioned cookies work. Site A embeds an iframe from Site B which uses JavaScript to set two cookies: a partitioned and unpartitioned cookie.

If third-party cookies are blocked you will only see __Host-partitioned-cookie=123 in the Site B iframe.

If third-party cookies are allowed you will see unpartitioned-cookie=456; and __Host-partitioned-cookie=123 in the iframe.

For more details follow the demo walkthrough.

Test the behavior with third-party cookies blocked

Use Chrome 114 or higher.
Open Settings > Privacy and security.
Click Third party cookies.
Select Block third party cookies.
Reload the page or click Go to Site A

You will only see __Host-partitioned-cookie=123 in the Site B iframe.

Click Go to Site B

When you are on Site B the unparitioned cookie is not in third-party context so it's not blocked and you will see unpartitioned-cookie=456; and __Host-partitioned-cookie=123.

Clear cookies

To reset the demo, clear all cookies for the site:

In Application > Storage > Cookies >
Right click on https://chips-site-B.glitch.me
Click Clear