Site A

This demo walks you through how partitioned cookies work. For more details follow the demo walkthrough.

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 one cookie in the Site B iframe:

  • __Host-partitioned-cookie=123

If third-party cookies are allowed you will see two cookies in the Site B iframe:

  • unpartitioned-cookie=456;
  • __Host-partitioned-cookie=123

Test the behavior with third-party cookies blocked

  1. Use Chrome 118 or higher.
  2. Set the chrome://flags/#test-third-party-cookie-phaseout flag and restart Chrome.
  3. When you load this page, you should only see one cookie in the Site B iframe.
    • __Host-partitioned-cookie=123
  4. Click Go to Site B
  5. When you are on Site B the unparitioned cookie is not in third-party context so it's not blocked and you will see two cookies:
    • unpartitioned-cookie=456;
    • __Host-partitioned-cookie=123.

Clear cookies

To reset the demo, clear all cookies for the site:
  1. In Application > Storage > Cookies >
  2. Right click on
  3. Click Clear