Cross-Origin-Opener-Policy header present

Questions about this rule

Does SEC_COOP affect my score?

No. It is a detection rule: it runs, appears in your report and never penalises you. "Cross-Origin-Opener-Policy header present" is information about the page rather than a defect - most pages are not expected to satisfy it.

What does SPECIFICATION confidence mean?

A standard says so: HTML, WCAG, an RFC or Google's own documentation. Confidence is a declared tier rather than a per-rule number, so every rule backed by the same class of evidence carries the same weight - which is what makes the score reproducible instead of hand-tuned.

How do I check SEC_COOP on my own site?

Paste your URL into the box above and it runs only this rule, usually in a couple of seconds. It is also included in the Security checker and in a full scan.