Initiator domains

Initiator-domain conditions compare against the origin that initiated a request, not the requested URL.

initiatorDomains

The rule matches only requests initiated by a listed domain.

excludedInitiatorDomains

The rule excludes requests initiated by a listed domain. Exclusions take precedence over included initiator domains.

Subdomains match. Entries must be ASCII domain names; use Punycode for internationalized names.

Headerly always adds its own extension ID to excludedInitiatorDomains. This internal exclusion prevents profiles from affecting Headerly's extension pages and requests.

Requests do not always have a conventional website initiator. Test Service Worker and extension-generated requests separately when initiator matching matters.