Enable powerful browser APIs and defend against attacks
COOP is enabled with a single HTTP Response Header, requiring only a single line of code or config.
There is a safe test mode for COOP, meaning you can gather feedback about the impact on your site without any risk.
Cross-Origin Opener Policy allows you to mitigate dangerous attacks and have access to powerful browser APIs that require COOP to be enabled.
You can choose to use COOP for either of these reasons and still gain the advantages of both.
Alongside enabling Cross-Origin Opener Policy, you should also consider Cross-Origin Embedder Policy.