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HTTP Client Hints

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8942.
Expired & archived
Author Ilya Grigorik
Last updated 2019-09-12 (Latest revision 2019-03-11)
Replaces draft-grigorik-http-client-hints
RFC stream Internet Engineering Task Force (IETF)
OPSDIR Last Call Review Incomplete, due 2020-05-08
Additional resources Mailing list discussion
Stream WG state WG Document
Associated WG milestone
Submit Client Hints
Document shepherd Mark Nottingham
Shepherd write-up Show Last changed 2016-11-21
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to "Mark Nottingham" <>

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


HTTP defines proactive content negotiation to allow servers to select the appropriate response for a given request, based upon the user agent's characteristics, as expressed in request headers. In practice, clients are often unwilling to send those request headers, because it is not clear whether they will be used, and sending them impacts both performance and privacy. This document defines two response headers, Accept-CH and Accept-CH- Lifetime, that servers can use to advertise their use of request headers for proactive content negotiation, along with a set of guidelines for the creation of such headers, colloquially known as "Client Hints." It also defines an initial set of Client Hints.


Ilya Grigorik

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)