The HTTP Accept-CH response header is included in an HTTP message to indicate the types of hints that the server is willing to accept from the client.
The HTTP Accept-CH response header is part of the Content Negotiation process, and more specifically is part of the Client Hints mechanism that is intended to improve network efficiency. It can only be used over a secure HTTPS connection and is not supported by all servers or browsers.
In this example, the server includes the Accept-CH HTTP header in the HTTP response, letting the client know that it will accept
The HTTP Accept-CH response header is used by servers to inform clients concerning what Client Hints they will accept.