Connection Allowlists

Connection Allowlists is a feature designed to provide explicit control over external endpoints by restricting connections initiated via the Fetch API or other web platform APIs from a document or worker. The proposed implementation involves the distribution of an authorized endpoint list from the server through an HTTP response header. Prior to the establishment of any connection by the user agent on behalf of a page, the agent will evaluate the destination against this allowlist; connections to verified endpoints will be permitted, while those failing to match the entries in the list will be blocked. More details on the proposal can be found here: https://github.com/WICG/connection-allowlists