To make crossOriginIsolation easier to deploy on sites with OAuth/payment flows relying on popups, we would like Cross-Origin-Opener-Policy: same-origin-allow-popups to also enable crossOriginIsolation when served with an appropriate Cross-Origin-Embedder-Policy header. This would introduce a new COOP mode, with a few restrictions compared to regular COOP same-origin-allow-popups. However, this mode would be crossOriginIsolated, while still having access to any popup it opens through


Sites that wish to continue using SharedArrayBuffer must opt-into cross-origin isolation. Among other things, cross-origin isolation will prevent cross-origin popups from having access to their opener. This behavior ships today in Firefox, and Chrome aims to ship it as well in Chrome 92. As part of crossOriginIsolation, websites must send a Cross-Origin-Opener-Policy: same-origin header. COOP same-origin prevents pages with different top-level origins from being able to communicate with each other. This breaks many OAuth or payment flows that rely on opening a cross-origin popup that will communicate back with the page through window.postMessage for example. APIs like WebID or WebPayments will eventually solve the issue by providing developers with a way to build robust OAuth or payment flows without pop-ups through browser mediation. However, these APIs are not there yet, and will require significant changes from OAuth/Payment flow providers and users. we would like to find a solution that helps websites deploy COOP without having to implement a lot of changes to their websites.

Status in Chromium


No active development (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

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Intent to Prototype url

Intent to Prototype thread

Last updated on 2021-10-20